What is the meaning of 2 Peter 2:4?

* The two F.O.G. Bibles & Commentary below are currently a work in progress.

For if God did not spare the angels when they sinned, but cast them deep into hell, placing them in chains of darkness to be held for judgment;

Berean Standard Bible (BSB)

For if God didn’t spare angels when they sinned, but cast them down to Tartarus, and committed them to pits of darkness, to be reserved for judgment;

World English Bible (WEB)

For{G1063} if{G1487} God{G2316} spared{G5339}{(G5662)} not{G3756} the angels{G32} that sinned{G264}{(G5660)}, but{G235} cast them down to hell{G5020}{(G5660)}, and delivered{G3860}{(G5656)} them into chains{G4577} of darkness{G2217}, to be reserved{G5083}{(G5772)} unto{G1519} judgment{G2920};

Strong's King James

(4) For if יהוה YAHWEH didn't spare angelic messengers who deviated but rather held them captive in Tartarus, handed them over to chains of darkness and reserved for condemnation.

The F.O.G*

[4] For if God didn't spare angels when they sinned, but cast them into the darkest dungeons to be held for judgment;

The F.O.G Paraphrase

For if God messengers who sinned did not spare, but with chains of thick gloom, having cast them down to Tartarus, did deliver them to judgment, having been reserved,

Young's Literal Translation