A "connective" is using phrases like:
You might be wondering
You'll thrill to know
You might be thinking
Let me explain
You see, when you're writing copy, you likely have a lot of information you want to stuff into your ad or sales letter.
But your mind is afraid to jump into a new subject... a new paragraph.
Yet, you need to.
These "connectives" give you permission to change gears a little bit.
And they give the reader permission to accept that you're changing gears.
Hope that helps.