Boyd’s Bible Dictionary:

Place for herding sheep, especially at night
Usually built strong to keep out wild animals (Num. 32:1616And they came near unto him, and said, We will build sheepfolds here for our cattle, and cities for our little ones: (Numbers 32:16); 2 Sam. 7:88Now therefore so shalt thou say unto my servant David, Thus saith the Lord of hosts, I took thee from the sheepcote, from following the sheep, to be ruler over my people, over Israel: (2 Samuel 7:8); John 10:1616And other sheep I have, which are not of this fold: them also I must bring, and they shall hear my voice; and there shall be one fold, and one shepherd. (John 10:16)). The bold, cote, or enclosure was also the place where the sheep were collected at shearing time (Jer. 23:33And I will gather the remnant of my flock out of all countries whither I have driven them, and will bring them again to their folds; and they shall be fruitful and increase. (Jeremiah 23:3); Zeph. 2:66And the sea coast shall be dwellings and cottages for shepherds, and folds for flocks. (Zephaniah 2:6)), which was a season of festivity (1 Sam. 25:7-117And now I have heard that thou hast shearers: now thy shepherds which were with us, we hurt them not, neither was there ought missing unto them, all the while they were in Carmel. 8Ask thy young men, and they will show thee. Wherefore let the young men find favor in thine eyes: for we come in a good day: give, I pray thee, whatsoever cometh to thine hand unto thy servants, and to thy son David. 9And when David's young men came, they spake to Nabal according to all those words in the name of David, and ceased. 10And Nabal answered David's servants, and said, Who is David? and who is the son of Jesse? there be many servants now a days that break away every man from his master. 11Shall I then take my bread, and my water, and my flesh that I have killed for my shearers, and give it unto men, whom I know not whence they be? (1 Samuel 25:7‑11); 2 Sam. 13:2323And it came to pass after two full years, that Absalom had sheepshearers in Baal-hazor, which is beside Ephraim: and Absalom invited all the king's sons. (2 Samuel 13:23)). Hence “shearing-house” (2 Kings 10:12-1412And he arose and departed, and came to Samaria. And as he was at the shearing house in the way, 13Jehu met with the brethren of Ahaziah king of Judah, and said, Who are ye? And they answered, We are the brethren of Ahaziah; and we go down to salute the children of the king and the children of the queen. 14And he said, Take them alive. And they took them alive, and slew them at the pit of the shearing house, even two and forty men; neither left he any of them. (2 Kings 10:12‑14)).

From Manners and Customs of the Bible:

In this beautiful figure reference is made to the place of shelter for the sheep where they might repose at night, and be safe from the attacks of wild beasts. The modern sheep-folds of Syria, which no doubt resemble those of ancient times, are low, fiat buildings opening into a court, which is surrounded by a stone wall, protected on the top by a layer of thorns. A doorway carefully guarded forms the entrance. Sheep-folds are referred to in a number of passages. See Numbers 32:16,24,3616And they came near unto him, and said, We will build sheepfolds here for our cattle, and cities for our little ones: (Numbers 32:16)
24Build you cities for your little ones, and folds for your sheep; and do that which hath proceeded out of your mouth. (Numbers 32:24)
36And Beth-nimrah, and Beth-haran, fenced cities: and folds for sheep. (Numbers 32:36)
; 1 Samuel 24:3; 23And he came to the sheepcotes by the way, where was a cave; and Saul went in to cover his feet: and David and his men remained in the sides of the cave. (1 Samuel 24:3) Chronicles 32:28; Psalm 78:7070He chose David also his servant, and took him from the sheepfolds: (Psalm 78:70).