Tyche is the Goddess of good fortune, Lady Luck. She teaches us that every situation's outcome is determined by chance - so says the blurb.
The image I get in my mind's eye of this particular Goddess is of a chic woman who frequents casinos. You know the type, you read about them in novels, see them in the movies etc, they are always at the arm of the man who is gambling; mysterious, sparkling in appearance and always bringing luck to whoever's arm they are hanging off.
Another, less glamorous image I have in my mind's eye is that of a Fairy Godmother type. Not as cool as the above image, but still Lady Luck nevertheless.