How long does one year of UNI last? Like High school generally goes across 4 terms starting in February and ending in October, but when does UNI start and finish in one year?

I’m doing a Bachelor of commerce one year and would like to know how long Il be at UNI and how long the holidays will be and whether or not we’l be given extra study to do during the holidays?
This is for Universities in Australia – Victoria – Melbourne.