U+A644 Cyrillic Capital Letter Reversed Dze

The Wikipedia has the following information about this codepoint:

Dze (Ѕ ѕ; italics: Ѕ ѕ) is a letter of the Cyrillic script, used in the Macedonian alphabet to represent the voiced alveolar affricate /d͡z/, similar to the pronunciation of ⟨ds⟩ in "needs" or "kids" in English. It is derived from the letter dzelo or zelo of the Early Cyrillic alphabet, and it was used historically in all Slavic languages that use Cyrillic.

Although fully obsolete everywhere in the Cyrillic world by the 19th century, the letter zelo was revived in 1944 by the designers of the alphabet of the then-codified Macedonian language. The phoneme is also present in Greek (ΤΖ τζ) and Albanian (X x), both non-Slavic neighbours to the Macedonian language; all are a part of the Balkan linguistic area. In the early 21st century, the same letter also appeared in Vojislav Nikčević's proposal for the new alphabet for the modern Montenegrin language.

The most common early letterform (Ѕ ѕ) resembles the Latin letter S (S s), but it is also seen reversed (Ꙅ ꙅ) like the Latin letter Reversed S (Ƨ ƨ), or Z with a tail and a tick (Ꙃ ꙃ).

Abkhaz has Abkhazian Dze (Ӡ ӡ), with an identical function and name but a different shape.