The redirect operation > is used in conjunction with stdoutput 1 and stderr 2.
command > [/dev/null] 2>&1
2 Represents the stderror. The &1 here represents the first argument which is /dev/null
The character 2 represents the stderr which takes the entire errors printed to the screen and then appends them to the /dev/null which is the first argument represented by &1.
So the command demonstration will be the following:
$ du -sh /* > /dev/null 2>&1
This redirect command will dump the errors and the output to /dev/null.
Explanation: the default behaviour of redirection operator is to redirect the stdout and we are redirecting them to devnul and then we followup the command with 2>&1 which mentions the stderr 2 and then redirects is to /dev/null, which is denoted by &1 describing the &1 as the first argument which is /dev/null