The Hebrew word behind "plowing" is one letter from the word for* lamp, *and the NKJV footnotes the alternative.
Quick answer
Pride shows in the eyes and sits in the heart, and even the ordinary work of a wicked man is named alongside them. The verse widens from posture to output.
Read both lines
The first line gives two body parts and two postures, high eyes and a wide heart, which is the Hebrew way of saying arrogance from the outside and from the inside. Then the third item breaks the pattern, and this is where translators divide. The consonants can be read as nir, tillage or plowing, or as ner, lamp, and the NKJV takes the first while footnoting the second. Either way the claim is unsettling in the same direction: it is not only the wicked man's crimes that are named but his ordinary business, his field or his light, the parts of his life that looked neutral. Chapter 20 has just spent two verses on lamps, at 20:20 and 20:27, which is worth noticing but does not settle anything here.
Related: Proverbs 6:17 · Proverbs 16:5 · Proverbs 20:27 · Proverbs 15:8
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.