https://web.archive.org/web/20080309104350/http://etk.scener.org/?op=tutorial and
https://problemkaputt.de/gbatek.htm#gbacheatdevices if you are collecting links.
Cheats have three components in the base form
What form the cheat is, the general one being always write this address. There are some historical and practical considerations for why certain types exist but I will skip that one for this.
What location to look at for this*, where to write in the general one, others might be what to compare.
What data to use when you do, back to the always write thing then the data you write there**. The payload might also be a choice term here.
It can get a bit more complicated in that some cheats (or CPU instructions a bit later on) on some systems might have two pieces of input data and an output but the general principle still holds.
*This can be a bit abstracted, the GBA in this case pretty much always having its RAM data as most cheat making types care to twiddle it in the 02?????? region (
https://problemkaputt.de/gbatek.htm#gbamemorymap ) so a lot of things might skip the 02, certainly the 0 part, as it is always assumed and gain some characters to use for other things (multiples of 4 and 8 being nice for certain types of database and lookup).
**which can have some implications -- for Zelda hold the health low and for enemies it might put them in their last ditch fight routines, for the player especially at end game points where you have a bunch more hearts you might trigger the low health alarm as 3 hearts is now standard or you might be unable to shoot a power sword in those games that have that mechanic for full health. Some then find the current max health and set current health to that instead, assuming just giving you 20 outright does not work.
Yours looked to be a 0 code (0 being the form/code type) which is part of the setup for the cheat if using it on a real cart; sometimes it is nice to not have to select a game from a potentially thousands long list and more importantly for some it might need an address to hook (see also master codes) which is not necessarily easy to find on the hardware itself and might differ between games where emulators and to some extent flash carts don't care. Further to that the enhacklopedia link noted 0 did not have anything in the next few positions.
If it is a one line cheat then a the hold this address as might be a basic infinite health cheat would have a different form.
Replicating codes is a fine method of learning things. The main troubles will come if the maker of the code wants to be a bit flash and does something a bit lower level than might be needed, if there is a quirk that needs sorting (must lose battle, health drains to score at end of level, minigame using the same area and crashing/behaving oddly if normal gameplay health or whatever is held) or if there is anti cheat involved. The GBA having more of that than a lot that came before it (powerful enough to handle it and written in C for a lot of things which makes that sort of thing a bit easier to do) but not enough to tank things. If you do download a database and find something that looks overly complicated by all means ask on the forums and someone might be able to run through why something is doing what it does.