This is the 920th most frequent Japanese word.
良く
"Well" or "often."
'良く' is used here as an exclamation meaning 'well' or 'good', appreciating someone's actions or performance.
良くやった！
Well done!
'良く' is used here to mean 'often', expressing the frequency of his coming to the park.
彼は良くこの公園に来ます。
He often comes to this park.
'良く' is used here to mean 'well' or 'clearly', describing the manner in which the music is heard, emphasizing clear and good perception.