I don't think you need to explain cryptocurrency from the technical point of view. Just like we explain the internet: it is an information protocol. We did not explain about TCP/IP and IP v4 stuff. Just mention that it is a digital currency where money can be transferred quickly with a reasonable fee. And then show the wallet, how to transfer, and stuff...
Don't forget to add the part that, it values is meant to increase or decrease due to demand and supply ,so even if it's purpose is not yet adopted world wide , you can still hold it as an asset to use in future