"
The arena! The arena! This is our world stage
The arena! The arena! This is our death cage
Cannons in the distance! The distance!
Silver parachutes descend
"This is our world stage" I guess means it's their stage, they're being shown on television.
"This is our death cage" - they can't leave, they're caged in.
"Cannons in the distance" is the cannons that sound for every tribute that dies.
"Silver parachutes descend" is the parachutes that are put in the arena by sponsors.
This probably won't make sense unless you've read the books or seen the movies.