1260 Days
Gentiles [non-Israelites] will trample the city of God for 42 months or 3.5 years. Days are also used elsewhere in the Bible (cf Daniel) to symbolize years.
Background Reading:
Revelation 11:1-3
1260 Days
The Gentiles
11 I was given a reed like a measuring rod and was told, "Go and measure the temple of God and the altar, and count the worshipers there. 2 But exclude the outer court; do not measure it, because it has been given to the Gentiles. They will trample on the holy city for 42 months.