U+09BE Bengali Vowel Sign Aa

The Wikipedia has the following information about this codepoint:

The Bengali script or Bangla alphabet (Bengali: বাংলা বর্ণমালা, romanized: Bangla bôrṇômala, Meitei: বেঙ্গলি ময়েক, romanized: Bengali mayek) is the alphabet used to write the Bengali language based on the Bengali-Assamese script, and has historically been used to write Sanskrit within Bengal. It is one of the most widely adopted writing systems in the world (used by over 265 million people). It is one of the official scripts of the Indian Republic. It is used as the official script of the Bengali language in Bangladesh, West Bengal, Tripura and Barak valley of Assam Until recently, it was the usual script for the Meitei language in Manipur, but is being replaced by Meitei mayek. two of the official languages of India.

From a classificatory point of view, the Bengali writing system is an abugida, i.e. its vowel graphemes are mainly realised not as independent letters, but as diacritics modifying the vowel inherent in the base letter they are added to. It is written from left to right and uses a single letter case, which makes it a unicameral script, as opposed to a bicameral one like the Latin script. It is recognisable, as are some other Brahmic scripts, by a distinctive horizontal line known as a mātrā (মাত্রা) running along the tops of the letters that links them together. The Bengali writing system is less blocky, however, and presents a more sinuous shape than the Devanagari script.