Kiddush Cup in Hebrew language means sanctification. By saying the traditional blessing over the Kiddush Cup wine , we sanctify the Sabbath or the Jewish holiday by G-D command as says the Torah holy bible.
The Torah sanctified the Shabath as G-d has created the entire world in six days, and rested on the seventh day. The Shabath in Hebrew means stop action. The Torah has commended, in the 10 commandments, the Jewish people to keep and to remember the Shabath. An observant Jew has to behave by the sages books how to observe Shabbath by the 39 restriction rules. These thirty nine rules are the basic guideline as what is forbidden to do or what is allowed. These thirty nine rules derive from the action the Kohanim (Jewish priests) were doing in the temple the whole seven days.
On Shabath evening, or Jewish holiday evening, one has to recite the Kiddish over the wine cup so to honor the Beginning of the holly day.
This rule is repeated also after coming back from the synagogue , and before having the meal.
Kiddish cups during generation have had a lot of skilled artist and ingenuity. Silversmiths over generation created beautiful wine cups made in silver, ceramic and many different metals as well.
There are many opinions as what is the minimum quantity of wine demanded to the Kidush. After the blessing ,you must drink a mouthful sip and pass the goblet over to the rest of meal participants. The Chala ( the 2 pieces of whole bread ) must be covered by chala cover until the wine blessing is over.https://www.ebay.com/itm/164378722781