It's sacred by means of God having sanctified it (Genesis ch.2).
The Shabbat is a subcategory of sacred, since God sanctified it (Genesis 2) as one of the the sacred things.
On Shabbat, several blessings are recited to sanctify the day. The most notable are the Kiddush, which is said over wine to bless the day and commemorate creation, and the Hamotzi, which is recited over bread to acknowledge God's provision. Additionally, blessings are said during the lighting of Shabbat candles, welcoming the peace and rest of the day. These blessings help to create a sacred atmosphere and mark the transition from the weekday to Shabbat.
They prepare their children for Shabbat and light the Shabbat candles.
"Shabbat Shalom!"
They're called Shabbat candles (Neirot Shabbat in Hebrew).
Shabbat Shabbatot
After Shabbat, there is the Havdalah service.
Shabbat comes from the Hebrew word for sit/rest. Shabbat is the day of rest.
Shabbat Shalom (שבת שלום).Note: This means 'A peaceful shabbat'. The phrase "happy shabbat" is not a phrase that is traditionally used.
Shabbat shalom is a Jewish greeting which we say during the day of Shabbat. See also:More about the Jewish Shabbat
There is no issue with swimming during Shabbat, however, you wouldn't be able to shower after swimming until Shabbat ends. (Assuming you wish to be Shabbat observant.)
Judaism.See also:More about Shabbat