I don't even understand.
For champion points calculated in percentages, only the whole number counts. So the term "jump point" refers to when you spend enough CP in a star to change up to the next whole number. You "jump" or ignore the numbers after the decimal point. For example, 12.04% or 12.68% should be read only as 12%. You need to spend a certain number of CP to "jump" to 13%. Due to diminishing returns, you might have to spend a lot of CP to get only another 1% increase in that star. The jump points chart shows how many CP it takes to get from one whole number percent to the next.