The letter ñ distinguishes the standard Spanish spelling “quinceañera” from the unaccented form “quinceanera.”
Ñ is a separate letter in the Spanish alphabet, not merely an n with decorative punctuation. It represents a palatal nasal sound, similar to the “ny” sound in the English word canyon. In quinceañera, the ñ appears in the syllable -añe-.
English writing often drops diacritics when keyboards or databases lack Spanish characters, so quinceanera is widely seen and understood. Spanish orthography, however, preserves the ñ. The tilde over the letter is essential because changing ñ to n changes the spelling and can affect pronunciation.