Can someone explain Java?

Hey guys. For some reason, My guidance counselor enrolled me in a java class next year. I have NO idea what java is and what it can do.
Can someone help me here

What is Java?
What can it do?
How do you use it?
Is it difficult?
Do you recommend it?

any other info would be great. Also I have tries to read the offcial site, but I could not make sence of it, so please dont link there