Why are you angry and why are you scowling?
God used these rhetorical questions to tell Cain that he was wrong to be angry and scowl. They may also have been intended to give Cain an opportunity to confess that he was wrong. (See: rc://en/ta/man/translate/figs-rquestion)
If you ... will you not be accepted?
God used this rhetorical question to remind Cain of something Cain should have already known. AT: "You know that if you do what is right, I will accept you" (See: rc://en/ta/man/translate/figs-rquestion)
But if you do not ... you must rule over it
God speaks of sin as if it were a person. AT: "But if you do not do what is right, you will desire to sin even more, and then you will do sinful things. You must refuse to obey it" (See: rc://en/ta/man/translate/figs-personification)
sin crouches ... to control you
Here sin is spoken of as a dangerous wild animal that is waiting for the chance to attack Cain. AT: "you will become so angry that you will not be able to stop sin" (See: rc://en/ta/man/translate/figs-metaphor)
Languages that do not have a noun that means "sin" could translate this as "your desire to sin" or "the bad things you want to do."
you must rule over it
Yahweh speaks of Cain's desire to sin as if it were a person over whom Cain should rule. AT: "you must control it so you do not sin" (See: rc://en/ta/man/translate/figs-personification)