Meaning of "cleavage"

[All Potted Out]

"Exercising using hand weights is a good way of toning the arm, shoulder, and pectoral muscles. Toning the pectoral muscles can improve a woman's cleavage."

What does cleavage mean in this context?

[Pamela]

Hi Apo
cleavage stands for the cleft between a woman’s breasts in your example

[Yankee]

Hi apo

I'd say the sentence also suggests indirectly that a woman's breasts will increase in size.

Amy