"He visits us on the weekends."
Translation:Él nos visita los fines de semana.
los fines makes the answer plural. you could translate it literally as the ends of week which is weekends
You wouldn't say 'the weekends' unless there was something special about them (the weekends our parents are away).
I think it must be regional. Where I live (Arkansas, USA) it is common to say "on the weekends." It sounds very normal to me.
Is it singular because it translates literally to, "He visits us on the ends of the week."?