A Cerca De – (around, about) should be used when there’s an idea of a ‘future time’ or ‘distance’.
Ex. Só nos veremos daqui a cerca de 60 dias.
Ex. We will only see each other in around 60 days.
Ex. Estamos a cerca de 20 quilômetros do lugarejo.
Ex. We are around 20 kilometers from the village.
Acerca De – (about) is the same as saying ‘in respect to’.
Ex. Falávamos acerca do jogo de ontem.
Ex. We were speaking about yesterday’s game.