What is a done-for-you service? Well, let's imagine you own a social media marketing tool. If you offered a done-for-you service for that tool, you would be setting up and running the tool for your users instead of them having to do it themselves.
Now, how does this benefit you and the user? Well, the user may want to use your tool but may not have the time (just like most of us) so, what you're doing is, providing them an option to use your tool but not have to run it themselves.
How does this benefit you? Done-for-you services are normally charged at 10-15x the price of the tool itself, which creates a great additional revenue stream for your business.