This character is a Nonspacing Mark and is mainly used in the Devanagari script.
The glyph is not a composition. It has no designated width in East Asian texts. In bidirectional text it acts as Nonspacing Mark. When changing direction it is not mirrored. U+093C prohibits a line break before it. The glyph can be confused with one other glyph.
The Wikipedia has the following information about this codepoint:
The nuqta (Hindi: नुक़्ता, Urdu: نقطہ, romanized: nuqtā; sometimes also spelled nukta), is a diacritic mark that was introduced in Devanagari and some other Indic scripts to represent sounds not present in the original scripts. It takes the form of a dot placed below a character. This idea is inspired from the Arabic script; for example, there are some letters in Urdu that share the same basic shape but differ in the placement of dots(s) or nuqta(s) in the Perso-Arabic script: the letter ع ayn, with the addition of a nuqta on top, becomes the letter غ g͟hayn.