What is the significance of 12 in the Bible?

The number "twelve" is common in the Bible. There were twelve tribes of Israel. In Leviticus, there were twelve unleavened cakes of bread left in the temple as a sacrifice. There were also twelve disciples of Jesus. Jesus's childhood is first recorded when he is in the temple at age twelve. In Revelation, a multiple of twelve (144,000) is used to give the number of those who will receive salvation during the Great Tribulation. In Revelation, the New Jerusalem will be surrounded by twelve gates of pearl.
There are 187 places in the Bible where the number twelve is used. Twelve is considered a perfect number and it symbolizes God's power and authority. It also symbolizes the completeness of the nation of Israel, a theme which appears in Revelation.
https://www.biblestudy.org/bibleref/meaning-of-numbers-in-bible/12.html