If you want to go formal, you could say:
20s - dalawampung dekada ng buhay
30s - tatlumpung dekada ng buhay
etc.
But in most informal situations, most Filipinos would understand "twenties" or "thirties" or other English constructions of that nature.
eg. Oy, ang bata niya! Akala ko nasa mga twenties siya.
(Hey, they're [he/she] so young! I thought they were in around their twenties.)