Bitcoin has value because it is a great store of value. It's similar to digital gold, only gold is much harder to store, secure and move around than gold.
Bitcoin has value because you can transfer this value anywhere in the world where there is an Internet! And you can do it in minutes!
And you can't do it with gold or any other material object!
In fact, Bitcoin easily performs the function of money - the transfer of value!
This is very well put, I'll just add one more thing: aside fro the ability to easily transfer value Bitcoin is also a great store of value, and it allows you to safely store value in a similar way to gold, while at the same time being much easier to secure or move.