There normally isn't a command or file called
gnu refers to the GNU Project, and includes a number of distinct programs, including gcc, emacs, the Bash shell, the Coreutils suite (which includs commands like
mv, and so forth), and a number of other things. The goal of the project is/was to create an entire operating system.
On some systems, GNU tools might be installed in a special directory, perhaps
/gnu. On others, including most Linux-based (or "GNU/Linux") systems, the GNU tools make up a large part of the operating system.
There is no "current version" of GNU; each sub-project (gcc, coreutils, emacs, ...) has its own series of releases.
Incidentally, your question asks about the location of
/gnu, if it exists, is a location. And
find gnu is going to (attempt to) traverse the
gnu directory in your current directory. I suggest you need to study the workings of Unix-like file systems.