if you are familiar with the word "thus" in English, "a su ves" significa lo mismo por ejemplo: mi hermano estudia mucho. siempre lo veo leyendo, a su ves tiene buenas calificaciones.

Hello! Basically, I´m with George about his answer,but it isn´t fine at all. Mainly, "at the same time" means "al mismo tiempo".Like in that example: "Yo estaba cocinando al mismo tiempo que escuchaba la radio" (I was cooking at the same time than I was listening to the radio) It´s the same with "a su vez" But ," a su vez", also implies an independent course of action,related,inside the same time ratio.So, taking the example before... "Yo estaba cocinando, mientras que, a su vez, mi hermano preparaba la mesa" (I was cooking whilst my bro was dishing the table at same time) Can u see it? We could say than , "a su vez" = por su parte+a la vez"(by his side+at same time), OK? I Hope had been helpful. Bye!

at the same time = a su vez

lo entiendo ,muchas gracias~