So,erm...is this reparation thing really a thing, or just one question that gets thrown around under the 'look what our opponents care about lololol' ?
Not really have an opinion on the topic, but it seems to me there are plenty of topics more important at this point. And lots of loose ends without a real answer (who gets how much to do what with?

)
First I should distinguish between the three types as it pertains to ethnic groups of people that come under discussion.
1) American Indians/Native Americans. Not a single ethnicity and more a tribe by tribe/nation by nation basis but I will lump it all together as most laws do.
2) Japanese internment camp victims.
3) Descendants of slaves.
1) is less talked about and the current treaties, land given over and whatever else have largely sorted things. You occasionally get people given odd parcels here and there, and the occasionally overstep but for the most part it is fairly settled and not really talked about much.
2) In case you were unfamiliar then during World War 2 the Americans dragged people of Japanese descent and stuck them in camps lest they decide to kick off on American soil. No crimes committed, no aiding war acts, no suspicions of anything, just people of Japanese descent (even multiple generations at times). North of 100000 people being taken here. Eventually this got ruled all kinds of unconstitutional. As this also saw people suffer during it, possibly lose businesses, possibly lose houses and other such possessions and you can still find people that lived it, suffered it, and were possibly born into it then you can make a case. I don't know how much is still pending here as most of it was resolved in the decades afterwards (record keeping was fairly good here).
3) So the US was a bit late to this ending slavery party (not quite as late as some of the Congo stuff for your country but let us stay on topic). 1865 was it nationwide, with many states outlawing it long before then (1780 being the first). Chattel slavery was no doubt horrific but when you will have an exceptionally hard time finding someone that even met someone that remembered it being outlawed (you are already looking at exceptional lifespans and young when it happened to in turn tell someone young at the end of their life to be exceptionally old today) then one does wonder why you would do things.
3) is what we are primarily concerned with for this thread and most discussions in general. It is a term that has been bandied about for years. Skip to about 3:30 if you want, maybe a bit before that. Or just watch the main skit (starts with a news anchor).
https://www.dailymotion.com/video/x72ghp3
You could got a bit further for not everything ended in 1865 and was sunshine and rainbows from then on, especially not in certain parts of the US. Or if you prefer see Jim Crow laws (see segregation) which brings us up to 1965, and some also consider the reasons for the formation of ghettos in California and the like as people moved to escape those (see the Second Great Migration). Though again not everything happened overnight -- 1967 saw the US supreme court do Loving v Virginia to strike down a law saying races could not intermarry, one with similar laws in a bunch of other states. 1968 gave housing laws some teeth (also did some stuff for Indians but we can skip that one) and there was also a further one that year dealing with segregated schooling if you want to do Green v. County School Board of New Kent County.
If wealth is indeed generational then by theoretically denying people the chance* to do much at times until the late 60s (if not later) then some try to make the case there that things ought to be boosted, possibly with a fat cheque. Quite how said cheque gets to be calculated I do not know (is it means tested? What if your grandparents rocked up from Nigeria in New York in the 1970s? What if just one grandparent appeared then and the other from a free state going back to the 1700s? What if you are a mix?), even more so as records are understandably rather spotty. Others prefer to go with things like making sure black communities get a lift up with schools, further education grants, development grants, police, support services, healthcare and whatever else. Quite why it wants to be specifically black people rather than poor and underperforming in general I do not know (and no small amount of the people plumping for it would probably try to call me a racist for asking but hey).
*not that excuses much but one ought to look at the First Great Migration that happened from about the middle of world war 1 until about 1940 and what went there.
There have been bills put before congress for decades now
https://www.congress.gov/bill/116th-congress/house-bill/40 for the current one,
https://ibw21.org/commentary/my-reparations-bill-hr-40/ for some more historical stuff from the people doing it. Introducing a bill is nothing special though but at the same time it also means it can't be dismissed entirely as a fringe conspiracy theory or nonsense term. At the same time it is more a concept pondered mostly by the fringe US left and a few of its people that organise around being black (
https://thehill.com/homenews/house/437286-reparations-bill-wins-new-momentum-in-house says the congressional black caucus leader expressed support for it, and it enjoyed something like broad support from many members there) much like the fringe US right have their own nutjobs that don't represent anything like the majority. I have not yet seen what happened here in depth to see if it is just politicians trying to garner support by saying the right thing, someone throwing in random terms in questions for giggles or genuinely held policy positions.