This is the 12327th most frequent Spanish word.
limpian
"(They) clean."
In this context, 'limpian' shows the continuous duty as part of the subject's role, which involves cleaning.
Los empleados limpian las oficinas antes de cerrar.
The employees clean the offices before closing.
The word 'limpian' is used in an interrogative sentence, inquiring about the subject's action of cleaning.
¿Por qué limpian las ventanas tan temprano?
Why do they clean the windows so early?
Here 'limpian' is used as the verb form in the present tense indicating an active action performed by the subject (Ellos).