What is the meaning of ر?

The eleventh letter of the Acehnese alphabet, written in the Arabic script.

The tenth letter of the Arabic alphabet, called رَاء (rāʔ) and written in the Arabic script; preceded by ذ (ḏ) and followed by ز (z).

The twentieth numeral symbol of the Arabic alphabet (traditional abjad order, used for list numbering), written in the Arabic script; preceded by ق (q) and followed by ش (š).

second-person masculine singular imperative of رَأَى (raʔā)

The ninteenth letter of the Balti alphabet, written in the Perso-Arabic script

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

The tenth letter of the Hijazi Arabic alphabet, called رَاء and written in the Arabic script; preceded by ذ (ḏāl) and followed by ز (zāy).

The eighteenth letter of the Khowar alphabet, written in the Arabic script; preceded by ذ and followed by ڑ.

A letter of the Old Ruthenian alphabet, written in the Arabic script.

The thirteenth letter of the Xiao'erjing abjad, written in the Arabic script.

The eighteenth letter of the Kashmiri alphabet, written in the Arabic script; preceded by ذ and followed by ڑ.

The ninth letter of the Kazakh alphabet, written in the Arabic script; preceded by د and followed by ز.

The eleventh letter of the Malay alphabet, written in the Arabic script.

The sixteenth letter of the Pashto alphabet, written in the Arabic script; preceded by ذ and followed by ړ.

The twelfth letter of the Persian alphabet, called ره or رِ and written in the Arabic script; preceded by ذ and followed by ز.

D, Re (the second note of the fixed-Do solfège scale)

Re (the second note of the movable-Do solfège scale, i.e. the supertonic)

The fourteenth letter of the Punjabi alphabet, written in the Shahmukhi script; preceded by ذ (ẕāl) and followed by ڑ (ṛe).

The twenty-fifth letter of the Sindhi alphabet, written in the Arabic script; preceded by ذ and followed by ڙ.

The fourteenth letter of the Urdu alphabet, written in the Arabic script; preceded by ذ and followed by ڑ.

The tenth letter of the Uyghur alphabet, written in the Arabic script; preceded by د and followed by ز.

The nineteenth letter of the Yoruba alphabet, written in the Arabic script; preceded by پ and followed by س.

Source: wiktionary.org