If you don’t specify a number then the standard output stream is assumed but you can also redirect errors
> file redirects stdout to file
1> file redirects stdout to file
2> file redirects stderr to file
&> file redirects stdout and stderr to file
We used 2>/dev/null, so it gets error output and redirects the stderr to file, in this case a null file!
/dev/null is the null device it takes any input you want and throws it away. It can be used to suppress any output.