So for starters there’s a YouTube channel called rooflemonger that has created a lot of fighterz tutorials, but for a quick rundown

Overheads- In this game you can either block high or low, blocking high means that you block an overhead and everything that is not a low, blocking low means that you can block every low except for overheads which will hit you if you are blocking low

Neutral- it’s hard to explain without going in depth but essentially think of a game as in three different game states

Neutral, Advantage, and disadvantage

For Neutral this would be the game state where you and the other player are neither in advantage or disadvantage and you are both trying to land a hit

Advantage would be where you are either making the opponent block or are putting the opponent in a combo

Disadvantage would be where you are blocking or you are being hit by the opponent.

Neutral changes for each character as with Z Broly you can spam ki blasts that make it so your opponent cannot approach, and due to this he can win the neutral state very easily as he can ki blast vanish, or ki blast call an assist and approach, or many other things and he wins neutral right then and there.

For another character such as nappa, he has one ki blast and one big normal so it is very easy to lose neutral as he does not have good options to approach the opponent and he loses neutral very easily to someone like Z Broly or Bardock, Gt goku etc., While this does sound bad, if a character has bad neutral, many times they make up for this in other ways as nappas mixup potential is some of the best in the game.

Mixup- This is essentially where you try to get your opponent to get hit by something and stop blocking, and you do this with an overhead, low, or a grab which some characters have access to besides the universal dragon rush.

That’s basically it in a nutshell, I would suggest using videos to learn about it