What is the meaning of じゃ?

The hiragana syllable じゃ (ja). Its equivalent in katakana is ジャ (ja).

so, thenused for connecting to a reasonable conclusion, supposition

well; then; so

by extension from the "so then" meaning: bye, goodbye

to be

: generic name for a large snake; a heavy drinker

: a moral wrong; a bad attitude; maliciousness, wickedness; such a person

: short for 麝香 (jakō, musk); short for 麝香鹿 (jakōjika, musk deer)

Source: wiktionary.org