What is the meaning of ?

an open back unrounded vowel.

[ɑ]-coloring or a weak, fleeting, epenthetic or echo [ɑ].

A vowel letter with approximately the value of IPA ɑ.

A vowel letter with approximately the value of IPA ɑ.

A vowel letter with approximately the value of IPA ɑ.

Source: wiktionary.org