、。
He probably won't visit you tomorrow.
Literal
Tomorrow, he [topic-は] you [object-を] visit-not probably.
Negative future prediction. 訪問しないでしょう — polite でしょう attached to a negative verb gives 'probably will not visit.' 訪問する ('to visit') is the formal Sino-Japanese verb (over the everyday 行く 'go to' or やってくる 'come over'); it takes を to mark the person being visited. The pronouns 彼 and あなた are more common in textbook Japanese than in natural speech, where they'd usually be replaced by names or dropped.