In almost all chess games one of the players wins by first obtaining a material advantage. The easiest way to obtain such a material advantage is to take the free pieces offered by the other player.

One way to localize these pieces is to look at each of your own pieces to see whether one of them can take the piece that just moved. Another way to localize these pieces is by starting from this piece itself and look on the same line or file for rooks and queens, on the same diagonals for Bishops, etcetera.
Not all potential free pieces are to be found this way, but it is a good start for a beginning chess player. For a more experienced player it is also needed to look at the opponent’s pieces that were defended by the moved piece at its previous position.

Later on it will become more important to assure that the found potential free pieces are really free.

Some exercises