Pawn Chains
A group of pawns that protect each other on a diagonal is called a pawn chain. The only unprotected pawn in the chain is the base pawn at the back. Pawn chains can restrict the opponent's pieces and help each other advance in the endgame.
Sometimes, attacking the pawn chain on the base is not possible or is just simply not practical, and we need to challenge the pawn chain from the front.
Black has a pawn chain from b7 to e4, but white can attack it on the front and challenge the structure.
If black doesn't take the pawn on f3, white will capture the pawn on e4, and if black takes, the chain is slowly broken.
White recaptures with the bishop and places pressure again on the head of the pawn chain.