As a software development intern myself, I always put the emphasis during my internships on learning. Companies don't hire interns expecting them to already know everything in the field, they hire people who show potential and willingness to learn as they grow.
It definitely is a big jump from university computer science classes to working in a software development environment, and companies know that. Make sure you talk with your supervisor and team in your first few weeks so you can begin to learn how the team functions and also get an overview of the projects that they are currently working on.
I also like to take time at the beginning on a new internship to learn about the frameworks and languages that are being used on the projects. If the company doesn't have its own learning platform, I will either checkout some playlists on YouTube or find a course on a platform like Udemy. For me, internships are all about learning, so I try to take advantage of all the resources around me. Utilizing both online courses in software development areas and talking to my coworkers about their work and skill sets so that I can learn about what it actually is like to work on a software development team.
Once you are actually able to get started on working on a project, don't be afraid to ask questions to your team! Even when you've done an online course and familiarized yourself with a new language, you still won't know all the answers. Use the experience of the people around you to your advantage, they will be able to teach you skills that no online course ever will.
I hope this answer provides a bit of insight! Best of luck!