Jesus continues teaching the disciples that they need to be humble like a child if they want to be important in God's kingdom. (See: [[rc://en/ta/man/translate/figs-simile]])
The phrase "kingdom of heaven" refers to God's rule as king. This phrase is used only in the book of Matthew. If possible, keep "heaven" in your translation. Alternate translation: "in God's kingdom" or "when our God in heaven establishes his rule on earth" (See: [[rc://en/ta/man/translate/figs-metonymy]])