Answer:
It is describing the main characteristics of the person who, according to the text, is considered more suspicious of being the real author of Shakespeare's work.
Step-by-step explanation:
The text talks about Shakespeare´s work. It tries to prove that the real author could not have been someone who had only born with exquisite talent for writing; that someone must have had college education in order to produce such works of art. Thus "courtier poet of middling talent" is defining the characteristics that the main suspicious of being responsible must have had.
Courtier: that is related to royalty (in order to pay for studies)
Poet: Title of his education
Middling talent: That wasn´t born knowing how to write beautifully, but has lots of practice on doing it.