What is the meaning of ء?

Hamza (ء) is a sign in the Arabic script that represents the glottal stop /ʔ/. It can be considered a diacritic or a letter, but it is not counted among the 28 letters of the alphabet. The exact spelling of the glottal stop depends on the combination of vowels that follow and precede it. It may be written with آ /ʔaː/, أ /ʔa/, //, /ʔu/, إ /ʔi/, ئ /ʔi/, //, ؤ /ʔu/, //, or, usually after a long vowel, ء.

همزه (hamza) — The twenty-forth letter of the Baluchi alphabet, written in the Perso-Arabic script.

and

marks the dative case

used to form the past participle when used after the infinitive

marks the genitive case

The forty-seventh letter of the Burushaski alphabet, written in the Perso-Arabic script

The thirty-third letter of the Malay alphabet, written in the Arabic script.

همزه (hamze/hamza, Hamza) – a character representing a glottal stop. It is considered a letter but is not counted as part of the Persian alphabet.

ہَمْزَہ (hamza, Hamza) – the thirty-fifth letter of the Urdu alphabet.

Source: wiktionary.org