。
Mr. Hirayama teaches very well.
Literal
Hirayama-teacher [topic-は] very skillfully teaches.
上手く (skillfully) is the adverbial form of the い-adjective 上手い ('skilled, good at'), describing the manner of 教える ('to teach'). Notice how Japanese can frame teaching quality in two different ways: as a noun-predicate description of the teacher (良い先生だ, 'is a good teacher') or as an adverb-modified action (上手く教える, 'teaches skillfully'). Different grammatical paths to the same compliment.