Simplify the following text for a Grade 6 native English-speaking person.
Original: An unusually low sperm count , not the same as low semen volume , is known as oligospermia , and the absence of any sperm from the semen is termed azoospermia .
Simplified: If there are an unusually low number of sperm in an ejaculation , this is called oligospermia . If there are no sperm at all , this is called azoospermia .