The Greek may also be translated, “He is near.”“It” would refer to the advent of Jesus. In either case the meaning is the same. The reading “He” is preferred in DA 632.
All these things.
This does not include the “sign” of the Son of man in v. 30, because when this is visible Jesus is already coming in the clouds—not simply “at the doors.” The expression “these things” goes back to the signs of v. 29, in particular, but also includes other events and signs Jesus mentions as taking place prior to the end. For a complete list of these see Mark 13 and Luke 21.
When ye shall see.
Emphasis is on personal recognition of the signs and an understanding of their import. Christians are to distinguish between the “great signs and wonders” of the false prophets (see on v. 24), and the true signs mentioned by Jesus. They are to differentiate between those things which Jesus foretold would mark “the beginning of sorrows” (v. 8) at a time when “the end is not yet” (v. 6), and the signs that would indicate that His return “is near, even at the doors” (v. 33).