My manager was friendly, easy to reach out to and very technical, having worked on the codebase themselves prior - being good at estimating complexity. I was given the next-senior software engineer on the team as a buddy throughout the internship period who was incredibly helpful at getting me off the ground, with frequent constructive feedback.
Managers were again arm's reach, had one-on-ones every other week. In terms of mentors, it depends on who your manager is. My first manager was a tech lead, so i could learn about technical stuff, but my second manager was a product manager, and they gave me good life advice, like always document your work, etc. Enjoyed working with both of my managers.
My mentor has been extremely kind and welcoming to me, always answers my questions when i need help.