Here are some articles from the web to describe the true meaning of the 12 days of Christmas.
The 12 days of Christmas in Christian tradition signifies the time between the birth of Christ and the arrival of the three wise men, also known as the Magi. It starts on December 25, which is celebrated as Christmas Day, and lasts until January 6, which is the Epiphany, also referred to as Three Kings' Day.
12 Days of Christmas Carol - Lyrics Meaning and History (christianity.com)
Twelve Days of Christmas - Wikipedia
Merry Christmas!