en_tn/deu/16/10.md

with the contribution of a freewill offering from your hand that you will give

Here "hand" represents the whole person. Alternate translation: "and you will give your free will offering" (See: rc://en/ta/man/jit/figs-synecdoche)

according as Yahweh your God has blessed you

"according to the harvest which Yahweh your God has given you" This means that the people will base how much they offer on how much they harvested that year.