Ariana is right, but 'a few' CAN mean three or four, but - depending on the speaker - might mean more. It's best to think of it as 'some'.
'few' does mean a small number, but it's horribly FORMAL. Native-speakers tend not to use it, and just keep it for very formal writing.
Instead of saying 'Few people trust politicians', it's much better to say 'Not many people trust politicians'.