"Executable" means, as you guessed, that you can execute this file directly (i.e., it's not just a library or a collection of functions).
Specifically, this executable is designed to take input from a log being piped in to it. Since you're running it in PyCharm without that piping, it seems like it does nothing. See the project's wiki entry for an explanation on how this utility should be used.
SLOC stands for Source Lines of Code - the number of logical lines of code in the file (as opposed to the number of physical lines). See the wikipedia article for some additional details about the differences between the two.