I'm afraid can also mean Sorry, when a request will probably not be fullfilled or attended. However, in order to perfom this function, a personal pronoun must come after afraid, also you can see that when talking about fearing something, it is usually proceeded by: ing. Pay attention to these examples:
I'm afraid of asking the teacher = I don't want to ask the teacher, I'm ashamed.
I'm afraid 'HE' has just left = Sorry, he has just left.
I'm afraid of diving into this sea = This sea may be deep, and I'm afraid of heigh.
I'm afraid 'Mr.Thompson' is busy in a meeting right now. = Sorry, but Mr.Thompson is having a meeting now, therefore he can't talk to
I’m sorry / afraid I can’t speak Spanish very well.
I’m sorry, can you say that again please?
I’m sorry / afraid his line is busy.
I’m sorry / afraid but he’s in a meeting at the moment.