The weapon you hold, on each job, gives you key binds 1-5. These are available from level 1. You can equip and swap weapons on the fly (usually 2 weapons at any given time).
1 is almost always a chain (so the 1-2-3 skills on most FFXIV jobs)
6 is some kind of healing skill. You can pick which, and which you choose has different effects (eg fast but weaker Cure-1 like, or bigger party-wide, or a defense buff like a tank might use)
7-9 are your build-related skills.
0 is an "elite skill" which you can only have one a time; This is usually your trump card.
All of these have very visual icons that show what they do if you're familiar with the game.
They all tend to also have very unique/visual elements to them when you do them.
If that sounds like too few abilities, remember FFXIV isn't really THAT different, it just has more buttons doing essentially same things.
As in, we could easily just combine Interject and Low Blow, and just give an extra charge. (It's not like Stun really even works where it'd be actually useful)
Or, Rampart-Reprisal-Sentinel; Could just be 1 def. buff with charges. (Sure I guess there are niche uses in savage where you'd stack them but I don't know about that stuff).
The game has a rolling meta, that changes fairly regularly as the community figures out new synergies in skills. It's close to Path of Exile in this way.
In addition it adds specializations every expansion which is a similar jump from say, Archanist to Summoner or Scholar. It's the same core job but it adds a lot of lateral tweaking you can do. This is to say, we can both play the same job in GW2, but have VERY different builds and play styles.
The bad is that if you stop GW2 for a while and come back, you'll need to spend a minute re-checking your build(s), as they might no longer do what you set them up to do.