The vulva and its subcomponents have a number of uses. Here is a short list of some of the more common ones.
Nestled within the vulva is the endpoint of a liquid waste disposal system. The vast majority of the time when someone uses their vulva, it’s for urination.
Subsections within the vulva are often the primary source of sexual pleasure for people who have them. Certain components, such as the clitoris, can become particularly sensitive to stimulation in certain situations. Not everyone who owns a vulva will use it in this way.
For most vulva owners, a region located adjacent to the vagina will eventually begin redecorating itself as a nursery pretty much every month. If this nursery does not get a resident within that month, it will tear down what it built and throw it out, down the vagina. For many people, this is an annoying, unwanted process, but for others, it can be a welcome sign that a resident has not arrived, and for others, it can just be a thing that happens.
Some people who own a vulva enjoy using some or all of it with another person. On the other side, some people enjoy having a vulva they do not own used with them. Not everyone who owns a vulva will use it in this way.
Occasionally, often as a delayed reaction to certain activities with a partner (although that’s not always the case), the vulva will transform into a passageway by which a tiny human will be kicked out of the assembly floor where it had spent several months building itself. Not everyone who owns a vulva will use it in this way, not even everyone who hosts a self-assembling mass of cells known as a “baby”.