A Sabbath day was a day of rest, a holy convocation where no manner of work was to be done therein. The various Sabbath days were:
Leviticus 23:3 Six days shall work be done: but the seventh day is the Sabbath of rest, an holy convocation; ye shall do no work therein: it is the Sabbath of the LORD in all your dwellings. (This day was sometimes called the “weekly Sabbath day” because it occurred every week.)
Leviticus 23:5–7, 11 …the first month…And on the fifteenth day of the same month is the Feast of Unleavened Bread unto the LORD…In the first day (of the Feast of Unleavened Bread; the 15th) ye shall have an holy convocation: ye shall do no servile work therein…the Sabbath….
Leviticus 23:8 …in the seventh day (of the Feast of Unleavened Bread; the 21st) is an holy convocation: ye shall do no servile work therein.
Leviticus 23:21 And ye shall proclaim on the selfsame day (Sivan 6th; seven weeks after the Day of Firstfruits of Barley Harvest; 50 days after the first day of the Feast of Unleavened Bread), that it may be an holy convocation unto you: ye shall do no servile work therein….
Leviticus 23:24–25 …In the seventh month, in the first day of the month, shall ye have a Sabbath, a Memorial of Blowing of Trumpets, an holy convocation. Ye shall do no servile work therein….
Leviticus 23:27–28, 31–32 Also on the tenth day of this seventh month there shall be a Day of Atonement: it shall be an holy convocation unto you…And ye shall do no work in that same day: for it is a Day of Atonement, to make an atonement for you before the LORD your God…Ye shall do no manner of work…It shall be unto you a Sabbath of rest…from even unto even, shall ye celebrate your Sabbath.
Leviticus 23:34–35, 39 …The fifteenth day of this seventh month shall be the Feast of Tabernacles…unto the LORD. On the first day (of the Feast of Tabernacles; the 15th) shall be an holy convocation: ye shall do no servile work therein…in the fifteenth day of the seventh month…on the first day (the 15th) shall be a Sabbath….
Leviticus 23:34, 36, 39 …this seventh month shall be the Feast of Tabernacles…unto the LORD…on the eighth day (of the Feast of Tabernacles; the 22nd) shall be an holy convocation unto you…and ye shall do no servile work therein…in the…seventh month…on the eighth day (the 22nd) shall be a Sabbath.
Note 1: There are many people—even many Christians—who think that Sunday is the new weekly Sabbath day under the New Covenant. They think that the weekly Sabbath day was changed from Saturday to Sunday when the New Covenant came in when Jesus rose from the dead.
There is nothing in the Bible that says that the weekly Sabbath day was ever changed from the last day of the week (Saturday) to the first day of the week (Sunday).
This idea (of the weekly Sabbath day changing from Saturday to Sunday) came from the Roman Catholic Church in 321 A.D. when Pope Constantine (the first pope of the Roman Catholic Church) issued the “Edict of Constantine” declaring that Sunday (the Venerable Day of the Sun) shall be a day of rest for all people in the Roman Empire and the Roman Catholic Church.
However, under the New Covenant we do not have any commandments to keep any Sabbath days—including the weekly Sabbath day.
Note 2: There are some people—even some Christians—who say that under the New Covenant we are still supposed to keep the Sabbath days.
These people have no Bible verses for this, and these people are hypocrites because they don't even keep all of the Sabbath days themselves! They only (supposedly) keep the weekly (Saturday) Sabbath days!