en_tn/gen/38/18.md

seal and cord ... staff

A "seal" is similar to a coin with a design engraved on it, used to imprint melted wax. The "cord" was put through the seal so the owner could wear it around his neck. A staff was long wooden stick that helped in walking over rough ground.

he went to her

This is a polite way of saying that he had sexual relations with Hagar. See how you translated a similar phrase in Genesis 16:2. (See: rc://en/ta/man/jit/figs-euphemism)

she became pregnant by him

This can be stated in active form. Alternate translation: "he caused her to become pregnant" (See: rc://en/ta/man/jit/figs-activepassive)