Learn Italian: Siamo nella cantina, ma non possiamo uscirne. - We are in the basement, but we cannot get out of there.

Here, the clitic ne acts as a locative pronoun meaning "from there" or "out of it" (referring to the basement). To attach it to the infinitive verb uscire, you drop the final -e of the verb and add ne directly to the end.

Since there is a modal verb (potere), could I put the ne before it instead?

Yes! Because possiamo is a modal verb (a helping verb like can, want, or must), you have two choices for placing the clitic. You can attach it to the infinitive (non possiamo uscirne) or place it before the conjugated modal verb (non ne possiamo uscire). Both are perfectly correct and mean the exact same thing.

Would the sentence still make sense if I just said non possiamo uscire without the ne?

Yes, it would, but the meaning shifts slightly. Non possiamo uscire simply means "we cannot get out" or "we cannot exit." Adding ne specifically links the exit back to the location you just mentioned, making it clear you mean "we cannot get out of there."

Is cantina related to the English word "canteen"?