A female HR executive is required to set the example for the rest of the company, and most of the time, this means polished business formal attire. She will be the go-to authority for other employees who may ask her what is required of them; therefore, it stands to reason that she needs to be a perfect example.
Female business formal is very easy to define in the states; however, there are obvious items that may be added when speaking of other countries and regions. First of all, clothing must fit! This is not a position where one allows skirts to droop and jackets to lazily fall off the shoulders! Clothing must be tailored close to the body but not too tight to suggest someone is going to the dance club or bar! Second, the material MUST be of a serviceable variety - dressy! No comfy, stretchy, or cotton here. Clothing should be well-constructed, lined, and formal. Beyond these things, a skirt suit or a jacket and skirt cut from the same fabric is most appropriate. A well-tailored dress, with an appropriate lining, may be worn in lieu of the skirt suit, but ladies, you must have a jacket on hand to give you that serious professional look. Make sure that professional pumps, with a modest heel, are worn at all times. Hosiery too! Generally, if it is comfortable, it usually isn't appropriate, is it? Let's be honest.
In conclusion, if one follows these rules, one will not only look the part but also feel the part. This variety of attire actually forces the individual wearing it to maintain proper posture and decorum during the workday, which will lend said individual the respect she deserves from those she will be assisting!