Question

What does /bin/sh -c mean? What does -c do?

Answer 1

From the man-page of bash:

-c string

If the -c option is present, then commands are read from string. If there are arguments after the string, they are assigned to the positional parameters, starting with $0.

Example:

$ bash -c ls

will launch bash and execute the command ls.

/bin/sh is usually a symlink to a shell.