She also said that they understand that XRP shouldn´t be volatile before banks start use it. But what does it mean? And how they achieve it? If they manipulate the price to make it stable, then all XRP investors wouldn´t be pleased.

Another bullshit from them.
She thinks it shouldn't be volatile but it is.
She thinks it doesn't compete with stablecoins but it does.
If it doesn't compete with stablecoins then with what? She would probably like to see it compete with Bitcoin but it's never going to happen. Centralized coins don't compete with decentralized coins.