"And leave out the court which is outside the TEMPLE, and do not measure it,
Traditionally, the outer court has been the only place where non-Jews are allowed. Since the three previous temples: Solomon's, Zerubabel's, and Herod's, which was destroyed in AD70, the TEMPLE mount has been under Gentile control. Even today, the Dome of the Rock, a Moslem edifice, occupies the site. This is prophesied by Jesus in Luke 21:20-24.
Apparently, a pact will be made with the Antichrist (Daniel 9:25) which gives the Jews 3 1/2 years to rebuild the TEMPLE on that site. Even today, Jews have gathered materials for the temple utensils. The time is near for the rebuilding of the TEMPLE.
The TEMPLE is so protected from non-Jews that Paul was accused of bringing Greeks into the temple area, Acts 21:27-28-30, instead of leaving them in the court. Some scholars suggest that the reason the court is not to be measured is that the Gentiles already have been measured, 2 Samuel 8:1-2-8.
for it has been given to the nations (Gentiles); and they will tread under foot the holy city for forty-two months.
This part of the verse clearly indicates that for 3 1/2 years (42 months) the holy city is occupied, particularly the TEMPLE mount, by the nations. The expression 'the nations' usually is interpreted to mean non-Jews. Whether this is limited to Arabs, also of Abraham's seed, or wider, such as Russians, Americans, Africans, etc. is open to conjecture.
This time, 42 months, is terminated when the "times of the Gentiles" is finished, Luke 21:24. The "times of the Gentiles" began with Nebuchadnezzar, 2 Chronicles 36:1-21. Here are some related prophesies: Daniel 9:26-27; Daniel 11:40; Ezekiel 38-39; Zechariah 14; and Joel 2.
There is an interesting observation that pre-Tribulation rapture proponents make. For the true believers in Christ, there was no temple. True believers worship God in Spirit and in Truth, John 4:23-24. Furthermore, we are called to worship God in the heavenly sanctuary, Hebrews 10:19-22. If the true believers are, in fact, gone prior to these 3 1/2 years, then there is no reason to try to measure the non-Jewish believers. Some scholars interpret this verse in that manner.
Lastly, the 'holy city' has always referred to Jerusalem (not Mecca or Rome or any other religious 'headquarters' city). It is where the devil took Jesus to be tempted, Matthew 4:1-5-11. It also explains why Israel (and Arabs) get so much news coverage. Inherently, the spiritual side of mankind knows something important is going to happen there.