Facebook will move to the US a large amount of profit that it has kept
in Ireland(and paid hardly any tax on).
It will pay insufficient tax on these profits in the US, too, but more than
in Ireland.
The article uses the bogus term "intellectual property", which is
always confusing and vague. The concrete referent in this case is not
very concrete. It refers to artificial excuses that Facebook has created
to make various parts of Facebook pay royalties to the part in Iceland.
This is how Facebook moves its profits to Iceland where they are not taxed
much if at all.