One of the best-loved verses in Proverbs, deliberately paired in placement with 18:11.
Quick answer
The LORD Himself, everything His name declares Him to be, is a fortress you can run into. The righteous do exactly that and are set on high, the footnote's literal reading. Safety, in this verse, is not a place but a Person.
Read both lines
The first line builds the tower: the name of the LORD means His revealed character, mercy and truth, slow anger, covenant faithfulness, and that, says the proverb, is a strong tower, the highest defense an ancient city had. The second line puts it to use, and the verb is the verse's heartbeat: the righteous run to it, the verb of a person with something behind them. "Are safe" is literally "set on high," lifted beyond the weapons at the gate. The verse's realism should not be missed: the righteous still have things to run from. What they also have is somewhere to run.
From this side of the cross
The name has been spoken with a face on it: "God also has highly exalted Him and given Him the name which is above every name" (Philippians 2:9). Running to the name now means running to Jesus, and the tower's door has never once been shut on someone running for it.
Related: Psalm 61:3 · Philippians 2:9–11 · Hebrews 6:18
New King James Version®, Copyright © 1982, Thomas Nelson. All rights reserved. Full copyright information. Scripture provided by API.Bible.
Go Deeper
If this verse has been used to put weight on you that it was never carrying, ask about it directly.