A (А а; italics: А а) is a letter of the Cyrillic script. It commonly represents an open central unrounded vowel /a/, like the pronunciation of ⟨a⟩ in "father". The Cyrillic letter А is romanized using the Latin letter A.
A (Cyrillic) Wikipedia
The Cyrillic letter А was derived directly from the Greek letter Alpha (Α α). In the Early Cyrillic alphabet its name was азъ (azǔ), meaning "I". In the Cyrillic numeral system, the Cyrillic letter А had a value of 1.
Through history the Cyrillic letter Aa has had various shapes, but today is standardised on one that looks exactly like the Latin letter Aa, including the italic forms.
In most languages that use the Cyrillic alphabet – such as Ukrainian, Belarusian, Russian, Serbian, Macedonian and Bulgarian – the Cyrillic letter А represents the open central unrounded vowel /a/. In Ingush and Chechen the Cyrillic letter А represents both the open back unrounded vowel /ɑ/ and the mid-central vowel /ə/. In Tuvan the letter can be written as a double vowel. A a : Latin letter A
Ă ă : Latin letter A with breve, used in Romanian language and Vietnamese language.
Ä ä : Latin letter A with diaeresis
Â â : Latin letter A with circumflex, after used in Vietnamese letter 3rd.
Α α : Greek letter Alpha