Here "kingdom of heaven" refers to God's rule as king. This phrase is found only in the book of Matthew. If possible, keep "heaven" in your translation. Alternate translation: "to accept our God in heaven as their king" or "to enter God's kingdom" (See: [[rc://en/ta/man/translate/figs-metonymy]])
Jesus uses an exaggeration to illustrate how very difficult it is for rich people to enter the kingdom of God. (See: [[rc://en/ta/man/translate/figs-hyperbole]])