What is the meaning of "Lo Yavo El ha'Ir ha'Zos"?
Radak: He will not conquer it. He came to the city with his camp, outside Yerushalayim, and there his camp was stricken.
Radak (Melachim II, 19:32, citing Targum Yonasan): He will not enter this city.
What is the meaning of "Lo Yekademenah Magen"?
Rashi: He will not set a shield against it.
Radak (Melachim II, 19:32, based on Targum Yonasan): It is as if it says b'Magen; the prefix Beis is omitted. Shield-bearing soldiers are the first to fight a city.
Malbim: Even before shooting arrows, one bears a shield lest the city shoot arrows at him.
What is "Solelah"?
Rashi: It is a mound of earth to stand on it and fight against a city. One makes walls of sticks, and pours earth between them and is Solel (paves, compresses it). Radak (Melachim II, 19:32) - this is like the Targum 'v'Lo Yatzber Alah Malyesa', which is like "va'Yitzbor Afar va'Yilkedah" (Chabakuk 1:10).
Rashi: Some say that it is throwing big catapult rocks. However, "Yishpoch" does not apply to this. Also the Targum is unlike this.
Malbim: It is a mound from which they shoot arrows at the city. They will not shoot arrows, for they will not even build the mound!
