What is the meaning of ,?

Separates items in a list.

Separates clauses in a sentence.

Separates coordinate adjectives.

Optionally sets off quoted material that is the grammatical object of an active verb of speaking or writing.

Separates one element in a date from another.

Separates a region from a geographic place within.

Separates the surname from given name when the traditional order is the reverse.

Separates title from a name.

Marks elision.

Marks a noun or pronoun used independently when speaking to some person, place or thing.

Separates steps to do something in software.

The thousands separator used in some countries.

Used for the Indian numbering system.

The decimal separator used in some countries.

the suffix -(V)nce or -(V)nse (-ance, -ence, -anse, -ense, etc.)

the suffix -ity

final glottal stop (on a syllable with fully falling lexical tone).

High-falling lexical tone.

glottal stop (with falling lexical tone).

Source: wiktionary.org