Startup, active and recovery frames all mean different things.
As someone who is new to frame data, you don’t really need to look at anything except a move’s Startup, advantage on hit and and advantage on block.
Here is my best explanation:
Let’s say you hit your opponent with cr.LP. This has +6 advantage on hit. This means that any move with 6 or lower startup will hit, because the enemy is in hitstun for 6 frames after you have finished attacking. So assuming you execute properly, you can follow up with any move that has 6f startup or lower. This is called a link.
That data is useful to determine moves that can form block strings (by trying to use a combo that gives your opponent the least amount of time between moves), and potentially frame traps (combos that give them just enough time to reactively press a button, only to get hit by another of your moves, usually a move with quick startup). Obviously it has applications for understanding which moves combo into each other, as well.
The other reason you want to know each move’s startup is for punishing.
For example, in SF4 Ryu’s sweep is -14 on block. That means that, in SF4 if you block Ryu’s sweep, you have 14 frames to do stuff before Ryu can block. So, assuming you are in range, ANYTHING that has 14f startup or faster can punish Ryu’s sweep. Most characters’ Ultras start up in less than 14f, so almost every character in the game can punish Ryu’s cr.HK with Ultra.
So in SFxT (or any fighting game really), it will be important to look at other characters’ frame data in comparison to your characters’ fastest moves, so that you know which moves can be punished by what.
Active and Recovery are not as important right away. Active is just how many frames a move is out for, and Recovery is how many extra frames it takes to go back into Neutral after your recovery frames end.
