Questions & Answers about Hablan del infierno en la historia.
Hablan is the third-person plural present tense of hablar. It means they speak or they are talking depending on context.
In this sentence, the verb ending -an tells you the subject is plural and not I / you singular / he / she.
- hablo = I speak
- hablas = you speak
- habla = he/she/you formal speaks
- hablan = they speak / you plural formal speak
Spanish often leaves out subject pronouns because the verb ending already tells you who the subject is.
So hablan already contains the idea of they.
In Spain, this will normally be understood as they unless the context clearly means ustedes in a formal plural sense. Spanish does this all the time:
- Comen = they eat
- Viven = they live
- Hablan = they speak