You have to figure out what the next row of 4 cards will be.
There is a pattern in there somewhere, promise.
My Answer is:
9-Spades | Jack-Hearts | Ace-Spades | 5-Clubs
They are adding four upwards (rotating to Ace after King)
the suit appears to be that of the card above and left
Although I'm not 100% on the suit for the first one. If the top right card was 10 Hearts I'd be absolutely certain, so perhaps there's something else going on here than what first appears.
5 -> 6 -> 7 -> 8 -> 9
7 -> 8 -> 9 -> 10 -> Jack
10 -> Jack -> Queen -> King -> Ace
Ace -> 2 -> 3 -> 4 -> 5
After not being 100% happy with the answer above, I have come up with an alternate answer that would make sense of the suit thing:
9-Diamonds | Jack-Hearts | Ace-Hearts | 5-Clubs
If that is the correct answer I'll explain how I got that instead.