A phospholipase is an enzyme that catalyzes the hydrolysis of glycerophospholipids.

As shown in the image below, the phospholipid can undergo a hydrolysis reaction which will produce water.

Structural reaction scheme for What is a Phospholipase?
Figure. What is a Phospholipase?
Source: Wikipedia

The cleavage sites appear on all three fatty acid groups and the acronyms refer to the type of phospholipase.