。
I'll visit Mr. Brown at his home tomorrow.
Literal
Tomorrow I [topic-は] Mr.-Brown [possessive-の] residence [object-を] visit.
お宅 ('residence,' honorific) adds respect when referring to someone else's home — more polite than 家. 訪問します is formal 'to visit.' Specifying お宅 adds a subtly more refined courtesy compared with the alternative bare 'to visit Mr Brown,' suitable when announcing a planned visit to someone of higher status.