What does s permission means?
Solution 1:
s(setuid) means set user ID upon execution. If setuid bit turned on a file, user executing that executable file gets the permissions of the individual or group that owns the file.
$ ls -l /usr/bin/sudo
-rwsr-xr-x 1 root root 121144 Feb 28 2013 /usr/bin/sudo
In this s permission was given to owner, so it represents the file is executable and set-user-ID mode is set.
Source