If we asked your friends/colleagues what are your good and bad points?
The tutors want to find out how you believe other people see you, and whether you can find areas where you might improve yourself.
Think about your skills as well as your personal qualities here - your positive points might be that you are kind, considerate, honest, polite but also good at solving problems, leading a group, or adept at fieldwork.
In terms of “bad points”, just because the interviewers have phrased the question using these words, doesn’t mean you must answer it in the same way.
Instead, think about any skills you feel you could work on to improve them, and how you would go about doing so.
For example, you might say that you would like to build up more confidence in public speaking, and you are going to join a Toastmasters class to enable you to do this.
Don’t put yourself down in front of the tutors, and say something like “I’m not very good at...” or “I can be quite impatient sometimes...”.
Rather, see this as a chance to reflect on your weaknesses and show them that you are motivated enough to try and improve on them.