I've got quite a few of these. I might come back to this as I think of more things, but I'll start with a few I think are important
Frame - The smallest unit of time used when describing a fighting game. Since it's assumed the game is running at 60 fps, A "frame" is equal to 1/60th of a second. Often abbreviated as "-f", where the dash can be any number. For example, a 6f jab is one that finishes its start-up period in 6 frames, or 1/10th of a second, a throw-tech window of 30f will give you about 1/2 a second to break out of the throw, etc.
Active - A move that is "active" has finished the start-up period and is now able to actually hit stuff. Once the active part of a move ends, you get to . . .
Recovery - The vulnerable "end lag" after performing a move. Depending on the game, there are a few situational things you can do to "cancel" the recovery of one move into another move (this is how combos happen).
Reversal - A move with invulnerable start-up, and in return, a very long recovery period. These are very high risk moves, since it beats any aggressive action, but if it misses or gets blocked, you're in a lot of trouble. This one is often abbreviated to "DP", short for "Dragon Punch", the English name for Ryu's Shoryuken attack, since that move is the textbook example for a reversal.
Meaty - An attack performed "meaty" is timed carefully against a knocked down opponent so that they recover from the knockdown just as the attack goes active. Essentially, they stand up into the attack. This lets the attacker skip the start-up of their move (since the start-up happens while the defender is knocked down and can't do anything about it), and it forces the defender to either block or reversal. If they mash buttons or try to jump away or something, they'll get hit.
And this one doesn't apply as much as a general term that shows up all over the place, but it's still important to know and can be confusing if you don't know what it means:
Footsies - An elaborate game of poking and counter-poking that happens at the edge of a character's attack range. At least, that's how I understand it (this is a big term for Street Fighter, and I'm not really a Street Fighter player). High-level footsies usually involves a lot of dancing in and out of attack range, and a ton of feints and fake-outs. For example, purposefully whiffing a jab well outside the range where it will hit, hoping that your opponent will see your attack and try to punish, and end up overextending themselves.
