Here "kingdom of heaven" refers to God's rule as king. The phrase "kingdom of heaven" is used only in the book of Matthew. If possible, keep "heaven" in your translation. Alternate translation: "has learned the truth about our God in heaven, who is king" or "has submitted himself to God's rule" (See: [[rc://en/ta/man/jit/figs-metonymy]])
Jesus speaks another parable. He compares scribes, who know very well the scriptures that Moses and the prophets wrote, and who also now accept Jesus's teachings, to a house owner who uses both old and new treasures. (See: [[rc://en/ta/man/jit/figs-parables]])
A treasure is a very valuable and precious thing or a collection of things. Here it may refer to the place where these things are stored, the "treasury" or "storeroom."