You play eight white pawns against eight black pawns, and nothing else. Some teachers call it the pawn game. You win by getting one pawn to the far side of the board, by capturing all of Black's pawns, or by leaving Black with no legal move while you still have one. If neither side can move, it's a draw.
Pawns are the trickiest piece for a beginner: they move straight ahead but capture diagonally, and they can never go backwards. Playing with nothing but pawns makes those rules second nature, and it teaches the idea of a passed pawn, one with nothing in front of it to stop it.
There is no en passant in this game. Three difficulty levels change how far ahead Black looks, and on easy Black will often play a bad move on purpose so a beginner can win.