RobH_en_tn/jas/01/19.md

You know this

Possible meanings are 1) "Know this" as a command, to pay attention to what I am about to write or 2) "You know this" as a statement, that I am about to remind you of something that you already know.

Let every man be quick to hear, slow to speak

These sayings are idioms that mean people should first listen intently, and then consider carefully what they say. Here "slow to speak" does not mean speaking slowly. (See: rc://en/ta/man/translate/figs-idiom)

slow to anger

"not get angry quickly"