20 Any non-Israelite people who remained of the Amorites, Hittites, Perizzites, Hivites, and Jebusites—
20
There were still people left from the Amorites, Hittites, Perizzites, Hivites and Jebusites (these peoples were not Israelites).
21 that is, the descendants of such people who were still in the land because the Israelites weren't able to wipe them out—Solomon forced into the labor gangs that are still in existence today.
21
Solomon conscripted the descendants of all these peoples remaining in the land—whom the Israelites could not exterminate —to serve as slave labor, as it is to this day.