Find out equivalent resistance between x and y.please explain in detail.

Since you havent asked for the resistance till inifinity, the  last two resistance at the farthest end of X and Y will get cancelled as no current will pass through them So the circuit now gets simple.The three resistance are in series so Equivalent resistance R'= R+R+R = 3R

Now this R' is in series with the other two resistances connected with X and Y. So Equivalent resistance R_eq = R' + R + R = 3R+R+R = 4R

Sorry for the inconvenience caused due to my answer above. Actually i misinterpreted the question. The equivalent resistance will be 2R.

The last two resistance at the farthest end from X and Y will get cancelled as no current will flow throuth them. The next two resistances after that are short circuited . So the equivalent resistance will be 2R