This command shows the File Descriptor $($FD$)$ in this output.

The character after the number i$.$e $1$u$,$ represents the mode in which the file is opened:

$"$r$"$ for read,

$"$w$"$ for write,

$"$u$"$ for read and write.

What object$/$file$/$binary$/$rodent is being REDIRECTED INTO this running$/$listening process?