According to Wikipedia:

"Saint Andrew's Day, also known as Andermas is the feast day of Andrew the Apostle. It is celebrated on 30 November.

"Saint Andrew's Day (Scots: Saunt Andra's Day, Scottish Gaelic: Là Naomh Anndrais) is Scotland's official national day. It has been a national holiday in Romania since 2015. Saint Andrew is the disciple in the New Testament who introduced his brother, the Apostle Peter, to Jesus as the Messiah. He is the patron saint of Cyprus, Scotland, Greece, Romania, Russia, Ukraine, the Ecumenical Patriarchate of Constantinople, San Andres Island (Colombia), Saint Andrew (Barbados) and Tenerife."

Saint Andrew's Day is perhaps best-known as the official national day of Scotland and is celebrated amongst Scottish descendants throughout the world. The celebration of Saint Andrew as a national festival is thought to originate from the reign of Malcolm III (1058–1093). It was thought that the ritual slaughter of animals associated with Samhain was moved to this date so as to assure enough animals were kept alive for winter. But it is only in more recent times that 30 November has been given national holiday status.

You can learn a lot more about Saint Andrew's Day at https://en.wikipedia.org/wiki/Saint_Andrew%27s_Day and in dozens of other web sites.