Just what it says. John's writing down the prophesy that Jesus is giving him as Jesus told him to do (Rev. 1:19). ("Many peoples, and nations, and tongues, and kings" have read this incredible prophesy over the 2000 years since it was written.)
Why does Jesus say this to him at this point in the prophesy? Not sure but we know we are in the mid-point of Daniel's 70th week and as Daniel tells us, the 3 1/2-year midpoint is very important (Dan. 9:27). Daniel has just seen half the world killed in 3 1/2 years and he's probably exhausted, maybe hoping that's all. Jesus is probably strengthening him because he's telling him there's more but Jesus always provides the strength to do his will.
Chapter 11 simply tells us that for the last 3 1/2 years (v. 3) the two witnesses have been prophesying in Jerusalem but the beast is finally able to kill them (v.7).
Christ will rule with a “rod of iron.” When does that happen? Will he be ruling over the flesh?
During his 1000-year rule on the earth (Chapt. 20), he will be ruling over the remnant of Israel and their descendants, the only ones left in the flesh and in the world after the slaughter of Armageddon. He's not going to put up with any s..t. (Mainly political s..t like we're seeing today from corrupt career politicians.) What a day that will be.
Except those days be shortened, there shall no flesh be saved.
At the mid-point of Daniel's 70th week, when the deceiver pulls off his mask and declares himself to be God (Dan. 9:27; 2 Thess. 2:4), the remnant of Israel, the ones that paid attention to Jesus' warning (Matt. 24:15-20) flee to the mountains where the beast miraculously cannot get at them (Rev. 12:6,14). I believe this will be Petra in Jordan (Edom) where the beast cannot get to them (Daniel 11:41). I believe they will suffer in this place which has enough caves for the millions+ who will be there. There will be water and food there, but probably not much. These, the remnant of Israel, are the flesh that if God didn't shorten the length of days, they probably would all die.
Daniel John has just seen half the world killed in 3 1/2 years and he's probably exhausted, maybe hoping that's all.