Azoospermia is when a man's body doesn't have any sperm in his semen. You know how when you pee, sometimes you can see little white things in the pee? Those little white things are called sperm, and they help make babies. But sometimes, some men's bodies don't make any sperm at all. It's like their body forgot to make them.
Doctors can do some tests to figure out why a man's body isn't making any sperm. It could be because the tubes that the sperm travel through in the body are blocked or something went wrong in their development, or the man's body may not be making enough hormones to make sperm.
If a man has azoospermia, it can make it hard for him to have a baby. But sometimes, doctors can help. They may be able to use a special medical procedure where they take sperm from the man's body directly, and then put it into a woman's egg to make a baby. This is called assisted reproduction, and it helps some couples who have trouble having a baby naturally.