Albert Barnes Commentary Leviticus 23:2

"Speak unto the children of Israel, and say unto them, The set feasts of Jehovah, which ye shall proclaim to be holy convocations, even these are my set feasts." — Leviticus 23:2 (ASV)

The feasts - literally, the appointed times. So in (Leviticus 23:4), (Leviticus 23:37), etc. This section (Leviticus 23:1–38) sets forth for practical guidance how the Lord's appointed times, weekly as well as annual, related to the ordinary occupations of the people.

Holy convocations - Days of sabbatical rest for the whole people; they derived their name from gatherings for religious edification, which, in later times, were probably held in every town and village in the holy land. There were in the course of the year, besides the weekly Sabbaths, seven days of holy convocation (Exodus 12:16); (Numbers 28:18), (Numbers 28:25–26); (Numbers 29:1), (Numbers 29:12), (Numbers 29:35), with a distinction between them regarding strictness of observance (Compare Leviticus 23:3, Leviticus 23:28 with Leviticus 23:7).