I'm pretty sure that "achar" is typically to think/find (like "i find this important") while "encontrar" is to look/find.
I guessed they encounter food. x Encounter = to come upon. Why's that wrong?
Is the difference between "Achar" and "Encontrar" like the difference between "Find" and "Encounter"?
I understand that "Elas" means they but can't it also mean "the girls"? if not, then why not?
Elas is a pronoun is used for a large number of nouns (girls, women, ladies, policewomen, etc). Girls is a noun, specific.
Ok, but isn't "de" an indefinite article in Portuguese? Does this apply for all verbs?
no! it is a preposition and is used after a few verbs. it also means "from/of". its use differs from the French "de".