1. You have a nerve telling me what to do. - You have an audacity in reminding me what I have to do. (General) 2. You have the nerve to tell me what to do. - You are courageous to tell me what to do. (Fact)
First of all, I would not use the word "a" in sentence 1. I would either omit it or use the word "some" or "a lot of": - You have nerve telling me what to do. - You have some nerve telling me what to do. - You have a lot of nerve telling me what to do.
The three sentences above would be used after the other person has already told