I once worked as an intern back-end web application developer, and it wasn't too challenging because most of the frameworks I worked with had an immense amount of online resources to learn from. And the code base wasn't too big so it was easy to pick up on.
But at my new job I'm working with a 20+ year old enterprise code base that relies on internal tools with ambiguous documentation. I don't have a mentor assigned to me, but I do work closely with the lead engineer to ramp up. A good portion of what he says goes over my head, so I either ask for clarifying questions or take notes and do research on my own.
There's a lot I don't know. I made an effort to keep notes of everything my coworkers and lead engineer say, as well as documenting my progress in learning all the technologies. In some ways I'm expanding my knowledge daily, but I don't think it's quickly as I'd like, and sometimes when my coworkers ask if I understand how x or y works and I don't, it seems like I've made no progress on learning at all.
This is my 2nd month here. The first month I spent setting up my dev environment and waiting to be granted permissions to various services. Now that I have a real assignment, I slog through this massive code base and have no idea what I'm doing. I ask for help but have a lot of stupid questions and feel like I'm wasting everybody's time because I can't resolve things on my own. I generally have a good idea of what I don't know and how to learn it, but in a lot of cases I don't know what I don't know and thus don't know what to ask, or how to ask a good question.
Maybe I'm being too hard on myself since I've only just started working and it's my 2nd month, but a part of me feels like I should be getting better at figuring things out a lot faster.