1. General Knowledge
2. Current Affairs
3. General Mental Ability
4. Numerical Ability
5. Quantitative Reasoning (Simple application of basic mathematical concepts arithmetic/algebra geometry/mensuration/stat taught till Grade 8)
6. Logical and Analytical Reasoning

You must study these for CUET exam . Also , you need to have knowledge of domain specific subject as well. The syllabus of domain related subject is different for different courses and you can check out the syllabus for the same !