Need Advice on learning software development as an intern

I’m currently an intern at a SaaS startup and have a solid foundation in DSA from the grinding of LeetCode. However, I’m finding software development much harder than expected. I’m not sure if it’s this difficult or if I’m approaching it the wrong way. I am so lost in this process, having to look into the company codebase melts my brain, I know the structure and how all things are supposed to look but ohhh boy I cant figure out what tf is happening!!. So far, my tasks have mostly involved in fixing bugs, but now I’ve been assigned a feature to implement in the codebase. I’m struggling to understand how the codebase works, where to look for required parts, and what to modify or add to make the feature functional. I have no prior experience in professional software development, did only small projects from college. I want to do good in this internship and convert it into a full-time role, but I feel so lost. Can anyone guide me on how to approach this situation, what to focus on, and whether there’s anything specific I need to learn to improve my software development skills? Any advices from experienced developers are welcomed i really need some help!