Proverbs 15:18 New English Translation

¹⁸A quick-tempered person^[a] stirs up dissension,
but one who is slow to anger^[b] calms^[c] a quarrel.^[d]

Proverbs 15:18 tn Heb “a man of wrath”; KJV, ASV “a wrathful man.” The term “wrath” functions as an attributive genitive: “an angry person.” He is contrasted with the “slow of anger,” so he is a “quick-tempered person” (cf. NLT “a hothead”).
Proverbs 15:18 tn Heb “slow of anger.” The noun “anger” functions as a genitive of specification: slow in reference to anger, that is, slow to get angry, patient.
Proverbs 15:18 tn The Hiphil verb יַשְׁקִיט (yashqit) means “to cause quietness; to pacify; to allay” the strife or quarrel (cf. NAB “allays discord”). This type of person goes out of his way to keep things calm and minimize contention; his opposite thrives on disagreement and dispute.
Proverbs 15:18 sn The fact that רִיב (riv) is used for “quarrel; strife” strongly implies that the setting is the courtroom or other legal setting (the gates of the city). The hot-headed person is eager to turn every disagreement into a legal case.

New English Translation (NET)