🔼The name Sela in the Bible
The name Sela (or sometimes erroneously transliterated as Selah) occurs twice in the Bible. It belongs to a town to the southeast of the Sea of Salt, in the territory that first belonged to Seir, then to Edom, and finally to Moab.
When it was Edom's, Sela was captured by king Amaziah of Judah, who renamed it Joktheel according to 2 Kings 14:7. The Chronicler tells the same story, but leaves out the names Sela and Joktheel (2 Chronicles 25). The Chronicler also reports that Amaziah had foolishly hired soldiers from Israel but sent them home (with their pay) before the fighting commenced at the insistence of an unnamed man of God. And after the battle, Amaziah imported the idols of Seir and worshipped them, which was also not very clever.
The prophet Isaiah also mentions Sela, but by this time, about a hundred years later, it's a Moabite city (Isaiah 16:1).
🔼Etymology of the name Sela
The name Sela is the same as the noun סלע (sela'), meaning rock, crag or cliff:
The name Sela means Rock, and since Sela was obviously located in the same immediate area as the famous, now Jordanian town of Petra (which is the Greek feminine word for rock; the masculine word forms the name Peter), it's often stated that Sela is the same as Petra, but that's not wholly so.
The famous city hewn out of the rock that's now known as Petra didn't get going until the fourth century BC (Amaziah was king in the ninth century and Isaiah wrote in the eighth century). But the place now occupied by Petra appears to have been continuously inhabited since much earlier, and the names Seir and Sela also appear in very old Egyptian texts that speak of that general area.