The word quinceañera is formed from the Spanish phrase quince años, so its language is Spanish.
Spanish is spoken across Spain, Latin America, and many communities worldwide. The quinceañera tradition is particularly associated with Spanish-speaking Latin American cultures, although celebrations are also held by Latino families in countries such as the United States.
The word’s spelling includes ñ, a letter used in Spanish. Quince means 15, and años means years. Together, quince años refers to the age milestone traditionally celebrated by the event.
Portuguese and Italian also have Romance-language connections, but their words for 15 differ from Spanish quince. That is why the linguistic clue points specifically to Spanish rather than to another language with related vocabulary.