1)
What is the meaning of "Emnam"?
1.
Rashi: It is true.
2)
What are "Es Kol ha'Aratzos v'Es Artzam"?
1.
Rashi: Aratzos are the Medinos, i.e. the capitol cities. Artzam are districts around them. In Melachim II, 19:17 it says "Es ha'Goyim v'Es Artzam"; this means the same as here.
2.
Radak based on Targum Yonasan: They are the Medinos (big cities) and villages.
3.
Malbim: They are the Afrachiyos (districts governed by rulers under the king).