It's a move to block check.
WHAT IS THIS!!!?

Sigh... I know it is the Ruy Lopez -_-.. But what is this variation called?
It's an irregular "Open Variation". Good for white and not much seen, according to Game Explorer.

This is the Open Variation of Ruy Lopez (upto move 5. After 5. O-O Nxe4 book recommends instead of 6.Re1 6.d4 -MCO14)
What is this?