What is the meaning of ?

Feet

Minutes (as a fraction of a degree of arc)

Minutes (as a unit of time)

Derivative of

Complement of a set

Transliteration of the soft sign (ь), indicating palatalization of preceding consonants – more correctly the modifier letter ⟨ʹ⟩.

Transpose

Used to distinguish two or more points, lines, etc. with the same name

palatalization symbol in Slavic Phonetic Alphabet – more correctly the modifier letter ⟨ʹ⟩

marks stress.

Source: wiktionary.org