Negamax is a way for a computer to figure out the best move to make in a game. It's like doing math homework, but instead of numbers you have different moves in a game like chess or checkers. Negamax works by looking ahead at all the possible moves you and your opponent can make, and figuring out which one is the best.
Imagine you are playing a game of checkers. You can only move your pieces diagonally, and you want to get your piece to the other side of the board. But your opponent is also trying to do the same thing. You have to think ahead and figure out what your opponent might do next, and then what move you can make to counter their move.
Negamax helps the computer do this by assigning a score to each move. If the computer is playing as white, it gives positive scores to moves that benefit white, and negative scores to moves that benefit black. The bigger the score, the better the move.
Negamax uses a recursive function, which means that it looks at all the possible moves, and then looks ahead at all the possible moves from that move, and so on. It continues until it can't look ahead any further, and then assigns scores to each move. It then looks at all the scores and chooses the move with the highest score.
So basically, negamax is a way for computers to think ahead in games and figure out the best move to make, like how you think ahead in checkers to figure out the best move to make.