You can set up a classification for the variable in your report suite and then use Classification Rule Builder, as the moderator has indicated.
An alternative is to create a segment in which the value of the variable includes a particular parameter. For example, a visit segment in which the entry variable (e.g. Page Name, if an s.prop) contains "facebook" (see screenshot for an example of how you could set this up).

Next, you can drop this segment into a blank freeform table, just as you would a dimension (see screenshot below).

The drawback here is that you cannot combine segments and dimensions in the same table axis, so if you wanted to compare Page Names that included "Facebook" to pages that did not or pages that included other text, you'd need to create additional segments. You'd face a similar issue with the classification approach in that any variable value that doesn't meet the requirements for your Facebook RegEx will be labeled as "Unspecified" in the table.