"Then Jesus said to his disciples." Since this is a continuation of Jesus speaking from the previous verse, some languages may prefer not to say "Then he said to them."
Here "nation" is a metonym for the people of the nation, and "rise against" is a metonym for attack. The word "nation" represents nations in general, not one particular nation. Alternate translation: "The people of one nation will attack the people of other nations" or "The people of some nations will attack the people of other nations" (See: [[rc://en/ta/man/jit/figs-metonymy]] and [[rc://en/ta/man/jit/figs-genericnoun]])
The words "will rise" are understood from the previous phrase and mean attack. Alternate translation: "kingdom will rise against kingdom" or "the people of some kingdoms will attack the people of other kingdoms" (See: [[rc://en/ta/man/jit/figs-ellipsis]] and [[rc://en/ta/man/jit/figs-metonymy]] and [[rc://en/ta/man/jit/figs-genericnoun]])