In university, you will typically cover several programming languages. Typically, if you are doing a computer science course, you may learn one or several general purpose programming languages, and you will probably do the core web languages of HTML, CSS and JS, and typically a web server side language like PHP. However, it is also a good idea to learn another language, here is why.
You advance your skills and have more to write on your CV - by learning another programming language, you get better and more proficient over time. Also, you begin to see the similarities and differences between programming languages, allowing you to better see over time which may be better suited to different tasks.
It will be easier to learn other languages in the future - when you learn different languages and see the similarities between languages, it is more natural to pick up and learn different languages. The programming principles, such as design patterns and SOLID principles, will still be largely applicable, you will be mostly learning syntax differences, overall reducing the time needed to learn new languages.
It helps you in university projects for languages which you have learnt at university - given the fact that you’ve practiced more in a new language, you will be better prepared to take on projects in general at university.
It can be useful for your final year project - as you have a great amount of freedom and flexibility in your final year project over which technologies and languages you can use, you may find that there are languages which are better suited for your project, other than the ones you were taught at university.