Some translations set poetry farther to the right than the rest of the text to show that it is poetry. The ULB does this with the poetry in verses 6, 15 and 16, which is from the Old Testament.
No one knows for use whether the "kingdom of heaven" was present or still coming when Jesus spoke these words. English translations often use the phrase "at hand," but these words can be difficult to translate. Other versions use the phase "is coming near" and "has come near."
The reader should not understand these words in verses 3 and 6 to mean that Satan did not know whether Jesus was the Son of God. God had already said that Jesus was his Son ([Matthew 3:17](../../mat/03/17.md)), so Satan knew who Jesus was. He also knew that Jesus could make stones become bread and could throw himself off of high places and not be hurt. He was trying to make Jesus do these things and so disobey God and obey Satan. These words can be translated as "Show me your power if you are the Son of God" (See: [[rc://en/tw/dict/bible/kt/satan]] and [[rc://en/tw/dict/bible/kt/sonofgod]])