Okay kiddo, so a blackberry is like a special type of phone that people use to send emails and messages. But sometimes, people use their blackberry for work emails too.
Now, a blackberry enterprise server is like a secret mailbox where all the work emails go to and from your blackberry. It helps keep the work emails safe and secure, so no one else can see them.
The enterprise server also helps the people in charge of the work emails to control who can see them and who can't. For example, your boss might not want everyone to see a certain email, so they can use the enterprise server to make sure only certain people can access it.
Overall, the blackberry enterprise server helps keep work emails safe and organized, so everyone can do their jobs better.