What is the meaning of ꜣ?

The lowercase letter alef, used in most Egyptian transliteration schemes to represent the sound of the hieroglyph

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the Egyptian vulture (Neophron percnopterus) [Pyramid Texts; Coffin Texts]

a bird in general [11th Dynasty]

intensifying or emphasizing particle, indeed [Pyramid Texts to New Kingdom; Greco-Roman Period]

marks a statement as hypothetical or contrafactual

also, and [Greco-Roman Period]

to enter or set foot in (a place) [Second Intermediate Period papyri]

to tread [Greco-Roman Period]

only used in jrj ꜣ r gs; likely a variant of the verb ‘to tread’ above. [Second Intermediate Period papyri]

Source: wiktionary.org