The term implies three things:
First, it implies authority.
Ps 8:4 What is man that You are mindful of him, And the son of man that You visit him?
5 For You have made him a little lower than the angels, And You have crowned him with glory and honor.
6 You have made him to have dominion over the works of Your hands; You have put all things under his feet,
Second, it refers to the humanity of the Lord Jesus. Surely a son of man is a human being. Ezekiel was called "son of man" by God referring to his humanity.
Third, it refers to His being the Messiah who will come in glory and power.
Da 7:13 "I was watching in the night visions, And behold, One like the Son of Man, Coming with the clouds of heaven! He came to the Ancient of Days, And they brought Him near before Him.
