What to do after finish grande 12 high school

For somebody who have their specific goal they just study what they want to be like a doctor,teacher..

But if you don't have ,is it problem?
There're many university, many major so which one is suitable for you?
Does the subject require high knowledge of mathematics ? English?

Famous University in Phnom Penh:

UHS : university of health sciences cambodia
ITC : Institute of Technology of Cambodia
RUPP : Royal University of Phnom Penh
RUFA : Royal University of fine art
RULE : Royal University of Law and economic
RUA : Royal university of Agriculture

Limkokwing University‎
Inernational university
Setec University
HRU : HUMAN RESOURCE UNIVERSITY
AEU : Asia Euro University