what is meant by phagocytosis of sperm...?

Phagocytosis is the cellular process of engulfing solid particles or other cells. It is carried out by phagocytes. In order to prevent the fertilization, the IUDs are introduced in the uterus which release some toxic substances and increase the number of leukocytes that engulf the sperms.  In simple words phagoctosis of sperms means the process of engulfing the sperm cells by leukocytes called phagocytes.