Complex sentence: Fork attacks can be either "relative", which is when the attacked units are any of the pawns, knights, bishops, rooks, or queen (s), or "absolute", which is when one of the attacked pieces includes the king.
Split into simpler sentences: Fork attacks can be either'Relative', which is when the attacked units are any of the Pawns, Knights, Bishops, Rooks, or Queen (s). Or, the Fork attacks can be'Absolute', which is when one of the attacked pieces includes the King.