Project supervisors oversee the running of a particular project, helping coordinate the project members and giving advice. There's some level of commitment associated with that – you should be happy to respond to emails and point people in the right kind of direction. You're not required to hold people's hands through everything or teach something from the ground up, though.
The key responsibilities are:
If you have any questions or issues, please ask on IRC (#cusf on irc.srcf.net) or email firstname.lastname@example.org.
For anything to do with budget (having expenses approved, things purchased, etc) please email the treasurer (currently ag611).