Alaikumassalam wa rahmatullah,
Nihal is an Arabic and Persian name for boys and girls that means "newly planted tree", "young tree", "young shoot of a tree". It is derived from the N-H26-L root which is not used anywhere in the Quran, for this reason it is not a Quranic name, but Muslims can use it since it has a good meaning. It is pronounced [(NI)p] + [(HA)nd + p(L)ay], it can also be pronounced [(NE)ck] + [(HA)nd + p(L)ay] and [(NU)mber] + [(HA)nd + p(L)ay]. It is written as نهال in Arabic and Farsi, and can also be written as Nehal, Neihal, Nehalle, Nahaal, Nihaal, Nehaal in English.
Ilhan can also be used for girls. I have updated the page to reflect this.