All the n
option does is replace the user and group names with the numeric values represented by those names.
Compare the ls -ln
output to the ls -l
output to see the difference. (On many distributions, users are numbered starting from 1000, and any users in the 1 through 999 range are assumed to be "system" users. User 0 is always "root.") By default, the "primary" group for a user is a private group with the same number and name as the user.
The 4 is the number of hard links to that directory and the 4096 is the number of bytes used by the directory. (Actually, 4096 is probably the minimum block size used by your file system, so you'll only see 0, 4096, 8192, ..., as directory sizes.)
I will assume you understand the date and time numbers . . .