The general interpretation is that it's a story about a swagman (a migrant worker) who goes waltzing Mathilda (traveling with his bedroll) to a billabong (a deep pool), then drowns himself rather than getting arrested for poaching a jumbuck (a sheep) by the troopers (police) who were called by the squatter to the squatter (landowner).
When writing the song, Banjo Patterson used a combination of Australian hobo slang and native Wiradjuri terms, presumably to give a sense of national identity.
But there are plenty of different scholarly interpretations! There must be! Academics rarely make their name by publishing "I agree with the traditional interpretation!" And that's probably a good thing!
Some of these interpretations are to add historical context: that it was a socialist rallying song, or the death of Samuel "Frenchy" Hofstadter at Combo Lake, or maybe a tea commercial.
Some say that a swagman is a kind of giant goblin bogeymonster, and that it was stealing a jumbuck (a domestic hygeine robot) from the squatter (horse-mounted outhouse) by the billabong (giant glass sculpture). Others say that the swagman (a T-shirt and coffee mug distributor) was camped out by the billabong (sales convention) and grabbed a jumbuck (excellent merchanizing contract).
But why research these things when you can just make up your own facts and translations of words in other peoples' languages that you're not in any way qualified to discuss? It's time for the home game!
The song is about a "swagman" (which means:
) who goes waltzing Mathilda (which means
) and finds a jumbuck (which means
) by a billabong (which means
) but then he's accosted by a squatter (which means
) and jumps into the billabong. The whole thing is one big