I agree that universities should require students to do an internship before they graduate. Most of all, they can get many realistic experiences before they graduate. When I was a university student, I had a chance to do an internship in a bank as a salesman. I learned a lot of skills such as excel, and* presentation in a real office environment. Also, I received many* useful pieces of* advice from managers. As a result, I'm able to understand my major more clearly and i have a better idea about my future job.

Your version is good (subject to the comments others have made on specific grammar points). To show what a short but perhaps more impactful statement might look like, here is my version. I agree that university students should be required to do an internship to gain practical experience prior to graduation. When I was a university student, I had the chance to do such an internship as a bank salesperson. From this I learned many skills including how to use Excel and how to develop and make sales presentations. I also received helpful advice from my managers, which allowed me to solidify my choice of career path. Good luck!

It's good. Agree with "and" before presentation. I have no problem with .... much advice. For me, ...many pieces of advice... seems less natural. lots of advice... even better. a significant amount of ...? . As a general point, universities is plural, then students is plural, then you say "they" which could be either, untill you read the rest. It might flow slightly better if you avoided the pronoun, eg Most of all, students ... "Most of all" is ok. The main benefit is that ...? to understand about .... Often people understand something about something. To understand clearly is not wrong. yet, to be clear & to understand are similar. As a result, I could understand more of my major and my job in the future. As a result, I could understand more clearly how my major and my job in the future might go. As a result, I could understand more clearly working in my major and my job in the future. Just ideas to consider.