U+0B57 Oriya Au Length Mark

The Wikipedia has the following information about this codepoint:

The Odia script (Odia: ଓଡ଼ିଆ ଅକ୍ଷର, romanized: Oḍiā akṣara, also Odia: ଓଡ଼ିଆ ଲିପି, romanized: Oḍiā lipi) is a Brahmic script used to write primarily Odia language and others including Sanskrit and other regional languages. It is one of the official scripts of the Indian Republic. The script has developed over more than 1000 years from a variant of Siddhaṃ script which was used in Eastern India, where the characteristic top line transformed into a distinct round umbrella shape due to the influence of palm leaf manuscripts and also being influenced by the neighbouring scripts from the Western and Southern regions.

Odia is a syllabic alphabet or an abugida wherein all consonants have an inherent vowel embedded within. Diacritics (which can appear above, below, before, or after the consonant they belong to) are used to change the form of the inherent vowel. When vowels appear at the beginning of a syllable, they are written as independent letters. Also, when certain consonants occur together, special conjunct symbols combine the essential parts of each consonant symbol.

An important feature of the Odia language seen in the script is the retention of inherent vowel in consonants, also known as schwa, at both medial and final positions. This absence of schwa deletion, which is also seen in Sanskrit, marks it from the rest of modern Indo-Aryan languages and their equivalent usage in related Brahmic scripts. The absence of the inherent vowel in the consonant is marked by a virama or halanta sign below the consonant.