This character is a Lowercase Letter and is mainly used in the Cherokee script. Its uppercase variant is Cherokee Letter Hu and its titlecase variant is Cherokee Letter Hu.
The glyph is not a composition. It has no designated width in East Asian texts. In bidirectional text it is written from left to right. When changing direction it is not mirrored. The word that U+AB81 forms with similar adjacent characters prevents a line break inside it. The glyph can be confused with one other glyph.
The Wikipedia has the following information about this codepoint:
The Cherokee syllabary is a syllabary invented by Sequoyah in the late 1810s and early 1820s to write the Cherokee language. His creation of the syllabary is particularly noteworthy as he was illiterate until its creation. He first experimented with logograms, but his system later developed into the syllabary. In his system, each symbol represents a syllable rather than a single phoneme; the 85 (originally 86) characters provide a suitable method for writing Cherokee. The letters resemble characters from other scripts, such as Latin, Greek, Cyrillic, and Glagolitic, however, these are not used to represent the same sounds.