The object of the game is checkmate, so all point-count systems are rules of thumb at best. But the "primitive" values we teach beginners are surprisingly useful: bishops and knights are worth 3 pawns, the rook is worth 5 pawns, and the queen is worth 9 pawns.
Some years ago, IM (now GM) Larry Kaufman slightly revised these rules of thumb based on empirical data. I just happened across the article today while looking up something else: it's still fascinating.
To summarize Kaufman's improved rules of thumb: bishops and knights are worth 3¼ pawns (but add ½ pawn for the bishop pair), rooks are still worth 5 pawns, and the queen is worth 9¾ pawns.