The most common reasons for refusing a student visa are:

* financial incapacity — you haven’t shown sufficient funds, or access to funds, to pay your tuition and support yourself without relying on part time work in your chosen country. Foreign countries have highest costs of living, particularly in housing. You need to have enough for your tuition plus at least another a year for living expenses for studying in most of countries.

*Not a genuine temporary entrant. This can be difficult to prove. They take into account things like having strong reasons to return home after your studies (like needing to take care of family members, having property or business) and the employment opportunities in your home country for the qualifications you intend to study.

Can you apply again?

You can apply again but first you will need an approval from the university to do so.
If the university is giving you an approval that means the reason for rejection was rectifiable and they will issue offer letter or enrollment letter. With this you can apply for your student visa again and make sure you are providing with the complete documentation as per the requirements this time.