Use of "se".
Why do you say , they left as, "se fueron" and they stayed as, "se quedaron" but when saying, they talked, you say "hablaron" without using "se"?
2 Answers
This use of se (se fueron) indicates "they left" as opposed to "they went / were."
This second use of se indicates reflexive usage although grammarians could agrue its usage as being reflexive or not. It really differentiates between a person staying / being in a certain place (Me quedo aquí) and other usages somewhat idiomatic such as: Me quedan sólo cien pesos (I have only one hundred pesos left), ¿En qué quedamos? (What do we agree to), etc, etc, etc.
Hablar has no reason for se , It means only to talk / speak and is not used as reflexive.
se habla means is spoken as in se habla español
se fue means he/she left. without the se it means he/she went
se quedaron means they stayed.