Hidden folder in /Users/Shared that has MD5-encrypted name of another user
Your question appears to be slightly incomplete, however the first two files are standard unix "files".

. is the shortcut for the current directory;
.. is the shortcut for the directory up one in the tree.

A lot of Unix shells require you to completely specify the path to an executable when executing them from the command line, and an example you may have seen:

./Make


Is a request to execute the file Make in the current directory.

Similarly, using the command

cd ..


Is a request to change the directory to the parent of the current directory.

Your third file is not named in your question so I cannot provide an answer for that.