Which programming languages do I have to learn for ECE before joining an engineering college?

C for sure, irrespective of the department and university. You may want to learn Python for your projects. Learning MATLAB scripts will also be helpful. Check your university syllabus to know more.

You need just basic knowledge of programming languages like C and C+ which will be part of your first-year syllabus. So I will not suggest you to learn programming languages separately or to worry about them. Hope this will help you. You can ask if you have any queries in the comments section.