As of now, Xapo does not allow their users to buy Bitcoin. However, they are planning to add this feature in the future.
NOTE: WARNING: XAPO is not a recognized financial institution and is not regulated by any government or regulatory body. As such, there is no guarantee that the Bitcoin purchased on XAPO will be safe or that their value will remain constant. Additionally, XAPO does not provide any customer service or dispute resolution options in the event of a transaction gone wrong. Therefore, use caution when buying Bitcoin on XAPO and always do your own research to make sure you are getting the best deal possible.
For now, users can only store and send Bitcoin using Xapo.