Complex sentence: If a player touches one of his pieces and an opponent's piece, he must make that capture if it is a legal move, otherwise he is required to move or capture the first of the pieces that he touched.
Split into simpler sentences: If a player touches one of his pieces and an opponent's piece, he or she must make that capture if it is a legal move. Otherwise, he or she is required to move or capture the first of the pieces that he touched.