Adverbial
An adverbial is a word or group of words that provides information about when, where, why, how, etc the action or state described in a sentence takes place, or that makes some comment about what is said in the rest of the sentence:
Come quickly !
Tell me honestly what you think.
I'll tell her tomorrow.
The boys are both at school.
Honestly, from the way she behaves you'd think she was the queen.
To be frank, I don't thinl< that is the right way to solve the problem.