A method for filtering objectionable content
I am uncertain about this; however, if I had to make an educated guess I would say this means that users have a way to limit and control (or filter) the content that is shown in their feed, dashboard, et cetera.
A mechanism for users to flag objectionable content
On most social media platforms that incorporate networking and user interaction, the app developers include a small button or link that onChange allows the user to flag content that they have deemed inappropriate and/or offensive. Perhaps this is what they mean.
A mechanism for users to block abusive users
Again, on most social media platforms or platforms that incorporate user interaction, the app developers include a small button that onChange allows them to block a user that they no longer wish to interact with.