John Gill Commentary Leviticus 23:38

"besides the sabbaths of Jehovah, and besides your gifts, and besides all your vows, and besides all your freewill-offerings, which ye give unto Jehovah." — Leviticus 23:38 (ASV)

Beside the sabbaths of the Lord
The seventh day sabbaths, which were of his appointing, and sacred to his service and worship; on which, when any of the feasts fell, it did not hinder the observance of them, or the offering of the several sacrifices on them; nor were those of the sabbath to be omitted on the account of them:

and beside your gifts ;
either of the whole congregation, or of a private person, which they thought well to give of their own good will on these festivals, over and above the sacrifices enjoined:

and beside all your vows, and beside all your freewill offerings, which
you give unto the Lord ;
which seem to explain what is meant before by gifts.