"and the angels will be with him." If you translate the first part of the sentence with Jesus speaking in the first person, you can translate this as "and my Father's angels will be with me." (See: [[rc://en/ta/man/translate/figs-123person]])
This is an important title for God that describes the relationship between God and the Son of Man, Jesus. (See: [[rc://en/ta/man/translate/guidelines-sonofgodprinciples]])
Here "his kingdom" represents him being King. AT: "until they see the Son of Man coming as King" or "until they see the evidence that the Son of Man is King" (See: [[rc://en/ta/man/translate/figs-metonymy]])