The phrase "income ladder" refers to the different levels of income that people can earn. It represents a way to show the progression from lower incomes to higher incomes in society. Full definition
You begin by creating a bond / CD / fixed income ladder for ten years in which each year you get both interest and cash out bonds / CDs. (allfinancialmatters.com)
As I mentioned earlier, you can also implement a Lifetime Income Ladder using fixed deferred annuities with income riders (attached benefits), or you can get really fancy and use both immediate and deferred annuities at the same time. (stantheannuityman.com)