I agree with Mr M. It might be worth adding that it's often a euphemism; it appears to be talking about the way someone is constructed, and hence about how they move, how well co-ordinated they are, but more often it's a way of saying that you find them attractive.
I'd like to give the woman's perspective. To me, a well-put-together woman is one who is wearing attrractive and fashionable clothing, with beautifully matching purse, jewelry, shoes and other accessories.
I'd just like to point out something. Not all female go by that conventional definition of 'well-put together.' Well-put together, as a general statement, is that you look like you know how to carry yourself. This could be physically, or through your work habits and movements.
Physically attractive / in good physical condition.