If you have a new Ripple wallet it requires you to have 20 XRP maintaining balance, this is to prevent users to create multiple wallet/address and to avoid shared global ledger from growing excessively. It is just like opening a new bank account that also have requirements of minimum maintaining balance for your account to remain active, but unlike bank accounts that you can withdraw all your money, Ripple will not let you withdraw those 20 XRP reserve, it doesn't go anywhere it is just locked up in your wallet/address. Ripple company can reduce this in future but also need to be approved by consensus.