Why does it mention standing up one who fell?
Rav Sadya Gaon: It is very hard for one who fell if no one helps him to stand.
Rashi: If one learned too much (and was not able to remember), his friend will return it to him 1 . Or, if he stumbled and was not precise about what his Rebbi said, his friend will bring him to the correct understanding.
Ibn Ezra: If one gets sick [the other will help him].
Ri Kara: If one fathers children, he will have support in his old age.
Seforno: If one errs, the other will correct him. It is not common that two make the same mistake.
Metzudas David: Even if both will fall in a bad situation, one will stand up the other.
R. Avigdor: "Cherev El ha'Badim v'No'alu" (Yirmeyah 50:36) - a sword [should come upon] haters of (a euphemism) Yisrael, who learn Bad v'Vad (alone), and they become foolish.
What is the meaning of "v'Ilo"?
