This character is a Other Punctuation and is commonly used, that is, in no specific script. The character is also known as at sign and arroba (old Spanish unit of weight).
The glyph is not a composition. Its East Asian Width is narrow. In bidirectional text it acts as Other Neutral. When changing direction it is not mirrored. The word that U+0040 forms with similar adjacent characters prevents a line break inside it.
The CLDR project calls this character “at-sign” for use in screen reading software. It assigns these additional labels, e.g. for search in emoji pickers: ampersat, arobase, arroba, at mark, at sign, commercial at, strudel.
The Wikipedia has the following information about this codepoint:
The at sign, @, is an accounting and invoice abbreviation meaning "at a rate of" (e.g. 7 widgets @ £2 per widget = £14), now seen more widely in email addresses and social media platform handles. It is normally read aloud as "at" and is also commonly called the at symbol, commercial at, or address sign.
The absence of a single English word for the symbol has prompted some writers to use the French arobase or Spanish and Portuguese arroba, or to coin new words such as ampersat and asperand, or the (visual) onomatopoeia strudel, but none of these have achieved wide use.
Although not included on the keyboard of the earliest commercially successful typewriters, it was on at least one 1889 model and the very successful Underwood models from the "Underwood No. 5" in 1900 onward. It started to be used in email addresses in the 1970s, and is now routinely included on most types of computer keyboards.