Behold, he set him up a place— Where he erected a monument or trophy of victory to himself. That the word יד, iad, signifies a monument, we learn from 2 Samuel 18:18 where Absalom is said to have erected a pillar, and to have called it אבשׁלום יד iad Abshalom, the monument of Absalom: by which is signified either the space or area where the monument was erected, or the thing itself which was erected; as מצב matzab, a pillar; which name, in the above-quoted place, is synonimous with יד iad. Houbigant. St. Jerome says, that Saul erected a triumphal arch.
Related Commentaries of 1 Samuel 15:12
1 Samuel 15:12
12 And when Samuel rose early to meet Saul in the morning, it was told Samuel, saying, Saul came to Carmel, and, behold, he set him up a place, and is gone about, and passed on, and gone down to Gilgal.