Can anyone give an example of how the "in text domain" field can be used in Ultimate Brand

I'm trying to narrow the scope of where I'm replacing some text, e.g. without eliminating all references to it. So I'm not trying to make a global change. Unfortunately, I haven't found any examples of how to use the particular field titled "in this text domain". Do I put a full sentence there, but only the words I want changed in the first field? Or am I suppose to put the directory address of the code that produces the text? Not sure what to put there.