Quick answer
One man manages his expression, the other manages his road. The verse contrasts a performance with a direction.
Read both lines
Hardening the face is a brazen look, the refusal to show anything, and it is a strategy aimed entirely at observers. The second line answers with something that has no audience at all. Here the Hebrew offers a choice: the written text says the upright establishes his way, and the reading tradition, followed by the Septuagint, says he understands it. The NKJV takes the first and footnotes the second. Either way the contrast holds and is the point: the wicked man works on how he appears, and the upright works on where he is going.
Related: Proverbs 21:8 · Proverbs 20:24 · Proverbs 7:13 · Proverbs 4:26
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.