Sefer Imrei Noam explains this pasuk by first explaining the Gemara (Pesachim 11B) that says that matzoh is called “lechem oni” because “onim alav devarim harbeh (we answer many things upon it).”
Chazal ask (Taanis 8B) what to do at a time when there is both a famine and a plague. Since we cannot daven for two things at the same time, which one should we pray for? They answer that one should pray for the famine to be removed, and once Hashem provides food, He will do so for living people. Thus, the death of the plague will also be removed.
We see from this that if one needs several yeshuos, he should daven to be saved from hunger and poverty, and all his other problems will go away as well because removing poverty automatically annuls the other forms of suffering.
The same idea applies to one who is “impoverished of mind” (Nedarim 41A), and such a person can use the same tactic to save himself from his spiritual problems. Accordingly, when the Gemara says that lechem oni “answers many things” the intent is that if one focuses his tefillos in being saved from his spiritual poverty, he will be answered in many areas, both in ruchnius and in a gashmius.
With this in mind, the Imrei Noam explains that when the pasuk that Hashem will be “mafli”, it means that He will perform many wonders. It then says “between the livestock of the Jews and the livestock of the Egyptians”, which can be understood to mean that His wonders will provide salvation both for spiritual and physical matters. The way to merit this is to daven that “nothing of the Jews will die.” This is a reference to poverty (as a poor man is considered dead, Nedarim 7B). Thus, the pasuk is saying that if one davens to be saved from poverty of the mind, he will be saved from all other problems he faces.
