en_tn/lev/16/21.md

confess over him

"confess over the goat"

he must put that sinfulness on the head of the goat

Aaron's actions here were a symbolic transfer of the people's sin to the goat as a sign that the goat would bear the punishment for their guilt. (See: rc://en/ta/man/jit/translate-symaction)

wickedness ... rebellion ... sins

These all mean basically the same thing. Aaron is confessing every kind of sin that the people committed.