That you are not dating anyone else and you are not married.
It means "available".
To be available.
Both are grammatical. They mean slightly different things.
If you mean URETHRITIS it is available on GOOGLE.
No shizzit
the answer is here
he is single.
it means the item is available
It could mean a room that is available (but it's out of context)
state of an atom with for elements available.
Available for use at the discretion of the user
they're single or available (: