Pseudo code for CTR mode encryption
what is ctr + 1, ctr+2...?


ctr is the first 128-bit input value processed by the block cipher, ctr+1 is this number incremented by 1, and so forth. In practice, ctr is generally a combination of a 96-bit nonce and a 32-bit incrementing counter.


  Is EK(ctr) || EK(ctr+1) || EK(ctr+2)... an 'OR' operation? and what is its result?


No, || refers to concatenation in this example.


  Is CTR mode one-time execution and not using loop?


No, CTR mode implementations almost always use a loop, and process in increments of a multiple of the block size.