I still don't understand what incremental means. Can someone explain what 0.1% p.a incremental balance over 1st 20k means in simplified terms?

Does it mean that any amount over 20k will stay at 0.1%? Basically only 20k in the account will get 2%?

Also from age 27 onwards, interest rate will remain the same?

Sorry I dont understand these complex financial terms. Thanks for understanding.