When something is "available", it means that someone has it, and that people are allowed to use it. For example, an employee at a gym might say:

Free yoga classes are available on Saturday mornings.

You can also say that "there is ___ available":

There's coffee and donuts available in the lobby.

And "___ has ___ available":

We'll have some more available on Wednesday. 

I don't know if anyone's going to want to drink, but it's nice to have something available in case they do.