It used to https://wiki.gbatemp.net/wiki/The_Name_of_GBAtempGba temp. Stands for Gay Butt Art Temporal because the website started out as a gay porn site before it was bought by someone else who decided to use it to post GBA roms.
Pirating specifically isn't allowed on here, you're thinking of that iso site.
At the time of the website opening it was a ROM site and provided downloads to the latest 10 GBA releases. As ROM sites usually had a very small life expectancy before they ran into legal trouble and were shut down the website was therefore designed as a 'temporary' ROM site. Hence "GBAtemp".
Thanks I never understood the "temp" part, "GBA" was a no-brainer...
I was about to ask if anyone else thinks of it that way lol.GameBoy Advance Temp.