What is meant by “unmasking” ?
The way I understand it, as Hannity has explained it, is that sometimes our Government intercepts and records communications of officials of other Governments. Sometimes American citizens are talking with officials who are being recorded, and their identities become known. That doesn't mean that the American citizens are necessarily involved in something criminal. The letter of the law is that the identities of these American citizens are not to be released, or put another way - "unmasked." It is a felony to do so, and it carries heavy criminal and civil penalties.