As someone who had their quinceanera party, I'll try to explain this from personal experience.
You grow up your whole life seeing your older female relatives have their parties. You witness how happy it makes them and how entertaining it is. It puts you in the planning process and you begin plotting your party with your relatives and friends. A Quinceañera party is similar to a Bar mitzvah, a function to celebrate your coming of age.
A young woman spends a whole year anticipating her fifteenth birthday. In some families (similar to mine) you can’t do many things until your fifteen. You can’t wear any makeup, you can’t shave your legs, you can’t have a boyfriend, you can’t wear nail polish, etc. until your fifteenth birthday (special occasions allow for some freedom). You spend your whole life waiting to have the newfound independence that comes with being fifteen.
You're fourteen when you start planning your Quinceañera. You put together boards and choose a theme, and you get a group of your closest friends to be in your court. The practices for your special dance are amusing, usually met joking around between rounds of dancing. It’s uncomfortable at the beginning, but by the end, you guys end up looking great. A part of this journey to independence calls for finding the perfect dress. With the most popular being a sweetheart style ballgown dress. It makes it hard to move around in without forgetting even a real princess can't have their beauty without the distress.
Now it’s the day of your fifteenth birthday. You perform the waltz dance that took your friends months to practice. Quinceañeras involve a father-daughter dance. You spend the rest of the night dancing tirelessly. The high energy from a quinceanera party is, what I can properly describe as, an immeasurably beautiful night.