nohup means it will continue to run when you exit the shell.
> means redirect the standard output to a file
The file it is being redirected to is
$HOME/jenkins.log. You can find the value of
$HOME by running
2>&1 means redirect standard errors to standard output, so in this example will also go into
< /dev/null means read data in from
/dev/null. So if the script is expecting input it will read that instead of waiting for user input.
& means run as a background task, and return you to the command line.
If you want more detail, ask in the comments.