그게… · 그게 말이에요 (polite) · 그게 말이야 (casual)
well, the thing is … (hesitating)
Example
그게… 사실은 제가 깜빡했어요.
Well, the thing is… I actually forgot.
Word parts
Contraction of 그것이 'that (thing)' + the subject marker 이.
Good to know
Used when you hesitate before explaining something awkward. Literal use is common too: 그게 뭐예요? 'What's that?'