Block
When you block someone on social networks, you prevent your publications from seeing on that social network. Blocked users will not be able to follow you, send you messages or label you in photos. Blocked Twitter users will not be able to add you to lists. Blocked users can still @Mention in a publication, but this mention will not count on your interaction metrics.
However, keep in mind that it is very easy for blocked users to see the content you have publicly posted. Use the privacy settings of each social network to have better control over who sees each of your publications.