quejarse REFLEXIVE VERB to complain
Quejarse is a basic word, meaning to complain, which it’s useful to know. To complain about something the preposition you use is de:
Se quejaban de la falta de información. They were complaining about the lack of information.
If you want to complain about what someone is doing, the construction is de que followed by a clause with the verb in the indicative:
Los vecinos siempre se quejan de que Raúl tiene la radio puesta. The neighbours are always complaining that Raul has the radio on.
And if you’re happy enough with a situation, you use quejarse in a similar way to English:
¿Cómo te va todo? – No me quejo. How are things? – I can’t complain.