Shabbat is the seventh day of the week. It is a day of rest, no work should be done on it. The origin of this can be found in Genesis 2:3, among others
“And Gd blessed the seventh day and made it holy; for on him Gd rested after he had finished all the work of creation.”
and in Exodus 23:12
»You may work six days and do all your works. But the seventh day is a Shabbat to the Lord, on which you shall not do any work to your Gd, neither you, nor your son, nor your daughter, nor your manservant, nor your maidservant, nor your cattle, nor the stranger who is in your gates . «
Shabbat begins at sunset on Friday evening and ends after dark on Saturday evening.
On Friday evenings just before sunset, when the first three stars are visible in the sky, or when one can no longer distinguish a white thread from a black thread at dusk, two candles are lit with a bracha (a blessing). The traditional Jewish Shabbat celebration then begins at home or after the service in the community with kiddush. and a feast. The kiddush is a blessing over wine and after the ritual washing of hands, the blessing over the challot, the two Shabbat breads.
Shabbat is a sacred day of leisure and rest, all mourning is avoided. On Shabbat morning, the weekly portion of the Torah is read in the synagogue.
After the end of the Shabbat, the Havdalah (distinction) ceremony, by lighting the Hawdala candle, separates the sacred Shabbat from profane everyday life.