what actually the function for e(g,g)^xy I doing a project using ABE "Attribute-Based-Encryption" but i didn't understand what actually the function for $e(g,g)^xy$.
Just tell what's the calculation need to perform here. I gone through no of publications and thesis but i didn't understand this. 

$PK = (T_1 = g ^{t_1} , ..., T_{|u|} = g^ {t|U|} , Y = e(g, g)^ y )$

Using the above values how can i calculate PK.

Thanks in advance
This is a bilinear pairing used in cryptography. More precisely it's an evaluation of an appropriate pairing friendly elliptic curve equation.(1,2,3,4,5)