Fetching details from the dictionary...
closely; intimately
personally; in person
directly (experience); at first-hand
親しく話せる友人がいる。
I have friends I can talk with closely.
その二人は親しく言葉を交わしていた。
The two of them were exchanging words warmly.
学生時代から彼とは家族ぐるみで親しく付き合っている。
I've been on close terms with him and his family since our student days.