what does nafl(nafilah) mean in Islam prayer

In Islam, Nafl (or Nafilah) refers to voluntary prayers that are performed in addition to the obligatory (Fard) prayers. These prayers are not compulsory like the five daily prayers (Fajr, Dhuhr, Asr, Maghrib, and Isha), but they are considered optional and highly recommended. Nafl prayers are performed to earn extra reward from Allah and to seek closeness to Him. They can be performed at any time of the day or night, except during specific prohibited times.