'Freewill Offerings' in the Bible

"Speak to Aaron, and to his sons, and to all the children of Israel, and say to them, 'Any man of the house of Israel or the foreigner who resides in Israel, who offers his offering, whether it be any of their vows, or any of their freewill offerings, which they offer to the LORD for a burnt offering;

besides the Sabbaths of the LORD, and besides your gifts, and besides all your vows, and besides all your freewill offerings, which you give to the LORD.