It depends the verb is repetir (yo) Repito = I repeat (tu) Repite = You repeat (usted) Repita = You repeat El profesor dijo:= the teacher said -Repitalo = - repeat it. El profesor dijo:= the teacher said -Repita el trabajo = - repeat the work. Yo lo repito = I repeat it. Yo repio el trabajo = I repeat the work. Asd you can see "lo" is the direct complement, depending of the sentenci we use after or before a verb