This character is a Other Letter and is mainly used in the Arabic script.
The glyph is not a composition. It has no designated width in East Asian texts. In bidirectional text it is written as Arabic letter from right to left. When changing direction it is not mirrored. The word that U+0630 forms with similar adjacent characters prevents a line break inside it. The glyph can be confused with 6 other glyphs.
El Wikipedia tiene la siguiente información acerca de este punto de código:
La ḏāl (en árabe ﺫﺍﻝ, ḏāl [ðaːl]) es la novena letra del alfabeto árabe. En árabe clásico representa un sonido fricativo, alveolar y sonoro,[1] /ð/. En la numeración abyad tiene el valor de 700.[2]