had relations (literally knew): In some contexts, the Hebrew word meaning "to know" is a way to describe having sexual relations with someone (4:17; 19:33, 35). It is never used for animals, which mate by instinct.
With the help of the LORD: Eve fulfilled her God-given role of having children despite the negative effects of sin (see 3:16, 20).
I have brought forth a man: Cain (Hebrew qayin) sounds like a Hebrew word (qanah) that can mean “produce” or “acquire.”