Fig.: to get to the important part of something; to deal with the main issue

He's always saying he'd love to help us out, but when the time comes right down to it, he's never available

Dice sempre che vorrebbe aiutarci, ma quando si viene al dunque non è mai disponibile

Before coming down to brass tacks, please let me make a short introduction...

Prima di venire al sodo della nostra riunione, permettetemi una breve premessa...

Although this expression has been widely used since the late 1800s, its origin is not totally clear. The most likely theory is that it refers to the brass-headed tacks embedded in a store counter, at one yard interval, for measuring cloth. Therefore, getting down to brass tacks literally meant to get the exact length of the material to be sold