What is the meaning of -ga?

ending of the comitative case

Added to nouns to form adjectives.

mother

Diminutive suffix, used especially in familiar names for pets.

Used to form nouns denoting the action of the suffixed verb; -ion, -ing

Used to form nouns denoting the event of the suffixed verb; -ion, -ing

Used to form nouns denoting the object of the suffixed verb.

going

Used to make a verb into a noun with a related meaning.

the

to (dative case)

Source: wiktionary.org