These are basically Unix permissions.
r == read permission
w == write permission
x == execute permission
The first set is for the user who owns the file (rwx), the second set is for the user group (r-x, so it is lacking write permission for the user group), and the third set (r-x, same as group) is for all other users.
The dash,'-' at the start means it is a file, otherwise it will have a 'd' for directory.