You use actually to indicate that a situation exists or happened, or to emphasize that it is true.
One afternoon, I grew bored and actually fell asleep for a few minutes...
Interest is only payable on the amount actually borrowed.
You can use actually when you are politely expressing an opinion that
other people might not have expected from you.
-`Do you think it's a good idea to socialize with one's patients?'
—`Actually, I do, I think it's a great idea.'
A jail is a place where criminals are kept in order to punish them,
or where people waiting to be tried are kept.
Three prisoners escaped from a jail. = prison