What is verbal diarrhoea?
1) Careless (or casual) statements.
2) Writing (or talking) a lot and then not editing the result properly.
I think most writers have had that conundrum where they don’t know how descriptive they ought to get and/or how they should introduce a situation or character trait.
For example you could say “Theo has insomnia” or throughout your story you could consistently point out how Theo has trouble sleeping and allow the reader to figure it out for themselves that Theo’s an insomniac.
Hope that makes sense.