Here, "taille" refers to the waist measurement.
Here are a few more examples:
* "The dress was designed to accentuate her taille."
* "He had a very slender taille."
* "The sculptor paid close attention to the taille of the statue."
Note: "Taille" is a French word, and while it is sometimes used in English, it's more common in French-speaking contexts. In English, we typically use "waist" instead.