What does "on one's behalf" mean?
"On [someone's] behalf" means "in place of another" or as a representative of someone. When the speaker says "... accept this award on her behalf," he means that he is accepting the award in place of/as a representative of Meredith, since she is not able to be there to accept it herself. Ex: Meredith is sick, so I will do the work on her behalf. Ex: On behalf of my parents, I'd like to thank everyone for attending today.