Meaning of the word "so long" in English

What does "so long" mean in English? Explore the meaning, pronunciation, and specific usage of this word with Lingoland.

so long

US /soʊ lɔŋ/
UK /səʊ lɒŋ/

Exclamation

goodbye

Example:
Well, so long, I'll see you next week.
He waved and said, "So long!"