Isnt hard to understand. If you buy a 10 year $100 bond with a return of 10%, you get $10 a year return for 10 years, plus your $100 back at the end of it (hopefully).
But if those $100 bonds drop for some reason, worry about the economy of the country that issued them, or company, say by 50%, so they are being sold for $50, it means your return/yield is now 20% as the underlying bond still pays out the $10 a year for 10 years.
Some arg gov bonds (if not all) are inflation indexed.. so they might have a return of 5% + inflation, so if inflation is 5% your return should be 10%. Thats why the gov has understated inflation here, keeps their bond interest payments down from what i have been told..