Problem statement: Trying to set up a webserver and install a wordpress on it.while trying to install, came across this command "apache.apache" .Wanted to know what this command does?
chown is for changing the owner, in your case your are going to change the user and group owners of wp-content to apache, apache.
chown $user:$group $directoryname
and -R for recursive which means wp-content and all its files and sub directories
Please read the following guide that will help you to understand some linux basics that would be helpful in the future: Linux User Management