Colossians is a great book of the Bible because it absolutely centred on Jesus. It is a letter to the church in the Ancient city of Colossea. They’d heard the gospel from someone who lived in their city. Paul writes to them to make sure the gospel is absolutely clear in their heads & hearts. He want them to know Jesus and serve him.
Ruins of the ancient city of Colossae. Photo by A.Savin, Wikipedia
https://en.wikipedia.org/wiki/Colossae