Soon you will be able to spend the Bitcoins that you hold in your Xapo wallet all over the world, as they have just announced that they will be launching a global Debit Mastercard soon, tied up towards the balances of the Bitcoin wallet of the user.
This means that if you have 1 Bitcoin in your wallet and the Bitcoin value is $450, then you can spend $450 in real cash with the new Debit Mastercard from Xapo. The exchange rate is based on Bitstamp's rate and will be converted the second the transaction goes through.
It is possible to pre-order the card now, but you shouldn't expect to see anything until in a few months as the system is not fully developed yet. There will be a physical Debit Mastercard, which will have a $15 fee upon receiving the card, while you can also choose to get a free digital debit card, which can only be used in online stores.
Xapo is mostly known for their Bitcoin wallet and their Bitcoin storage functionality, also known as a vault. The vault provides offline storage of Bitcoins as well as full insurance on them in case of theft.