Saçları gece gibi simsiyah olan kadın; Çok karanlık gecede görülen ışık.

My attempt:
The woman's hair is jet black like the night. In the very dark night it can be seen gleaming

These are the definitions for the girls name "Leyla". They are probably taken from a website such as this one:
http://www.gebelik-rehberi.com/isim/kiz_l.asp

Here is the link to the official website of Turkish Language Institute. They have a dictionary for Turkish peoples names. Almost all names in Turkish have a meaning.

http://tdk.gov.tr/TR/AdArama.aspx?F6E10F8892433CFFAAF6AA849816B2EF0BF5B4755D05B9EB&sirano=5250
Translations in parenthesis are mine.

Leylâ
Köken (source) : Ar. (Arabic)
Cinsiyet (gender): Kız (female)

Anlam (meaning)
1. Gece. (night)
2. mec. (mecazi> figurative meaning) Saçları gece gibi simsiyah olan kadın (A woman whose hair is dark as night).
3. Arabî ayların son gecesi. (last nights of Arabian months)

whose light can often be seen in the nights darkness?

My daughters Leila (Leyla) - the meaning for it that i have in my book of names is "beautiful long black hair"

but my daughter's blonde