The writer of the First Book of Kings said of King Solomon,
King Solomon loved many foreign women, as well as the daughter of Pharaoh: women of the Moabites, Ammonites, Edomites, Sidonians, and Hittites—
A couple of sentences later, the writer said,
And [Solomon] had seven hundred wives, princesses, and three hundred concubines; and his wives turned away his heart (1 Kings 11.3).
Yes, Solomon loved many foreign women and he took 700 of them as wives and another 300 as concubines, totalling 1,000 women!
However, between the two parts I have quoted, the writer also said,
…from the nations of whom the Lord had said to the children of Israel, “You shall not intermarry with them, nor they with you. Surely they will turn away your hearts after their gods.” Solomon clung to these in love (1 Kings 11.2).
Therefore, seven in this instance does not significance anything good, unless it simply shows the completion of King Solomon’s fall, although I believe the Book of Ecclesiastes shows that he returned to the Lord.
Otherwise, this is an incidental reference to the number 7 in the Bible.