How do I describe that I have studied other courses along with my degree in BE in an interview?

If you are not able to relate the courses you did with a purpose in your life, the interviewer cannot appreciate it. Instead if you can show a project work you initiated with the skills you learned from the course you did, or if you are able to convince how your knowledge can be beneficial for the role you are being interviewed for, it will be impactful.

Your profile or Resume should capture your details and during the interview, you should be able to express why you did those courses.

If you are not able to relate the courses you did with a purpose in your life, the interviewer cannot appreciate it. Instead if you can show a project work you initiated with the skills you learned from the course you did, or if you are able to convince how your knowledge can be beneficial for the role you are being interviewed for, it will be impactful.

Your courses could be co curricular ( in alignment with your degree course) or extra curricular ( supporting your talents or a service to society). Both can reflect in your Resume ; also in your profile. Standard professional networks like LinkedIn has such inbuilt fields where you can write about you in respective areas, Also have features to endorse/ recommend you by your connections.