Working with a mentor can be scary - but it's also really exciting. You'll get to work with and learn from an engineer who has experience working with large scale codebases and rigorous software engineering practices. Therefore, you should take this opportunity to learn as much as you can.
Here are some tips which might help you when working with your mentor.
Be proactive about what you want to get out of the program (learning about software engineering, contributing to open source, etc) - and let your mentor know so they can guide you appropriately.
Clearly set expectations about the program - it's not about putting out the most contributions in a short time, but rather learning the process and making effective, impactful contributions.
Clearly set expectations about next steps - let them know what you're planning on working next and how much time you think it will take.
It's okay to have an unproductive week - sometimes technology gets confusing, or life gets in the way (exams, personal stuff) - that's totally fine! Just let your mentor know so they can plan accordingly and support you where possible.
Remember that at the end of the day, what you get out of this program is entirely what you put in to it. Make the most of the resources at your disposal.
Effective communication: work with your mentor to set expectations around availability and communication preferences - especially when there's a timezone difference. Ask them if they prefer email, or what times of day they're likely to be available for a more real-time discussion.
Make sure to have an open channel of communication - proactively let your mentor know when you're available and how best you can be reached (whether it's Email, Messenger, Skype, etc).
Communicate, communicate, communicate! When working on a change, if you have some work in progress that's working, or stuck, feel free to reach out to your mentor, and ask if they think your changes are structured correctly or how to improve them.
There's no such thing as a dumb question - if you're stuck on something, do reach out to your mentor and ask for help.
As a corollary to that, make sure you put in the effort before asking a question — as an example if you're stuck on some technical problem, try a few approaches, document what you tried (and why it didn't work), what documentation you looked at; and then share that with your mentor when you ask them for help. A general rule of thumb is to spend at least an hour before asking for help.
Open source projects often have documentation, and larger projects often have tutorials online - make sure to use them! Often you can find a solution to your problem there.
Ask your mentor how to effectively communicate on open source projects, and how to structure code, and write a good commit.
Working with a mentor is a skill in itself. If you're looking for more advice on how to handle a tricky situation with your mentor, do reach out to the program admins who should be able to help.