scoring during game

This shows the material difference between you and your opponent. Each piece has a value associated with it. Although material alone does not reveal whether you are ahead or behind in a game, it is a useful indicator of who has the advantage on the board.
You can take this quick lesson to learn more: https://www.chess.com/lessons/capturing-pieces/value-of-the-pieces
You can also reference this official article which explains more and gives some examples: https://www.chess.com/terms/chess-piece-value
From the article:
Piece | Value |
Pawn | 1 |
Knight | 3 |
Bishop | 3 |
Rook | 5 |
Queen | 9 |