Super Spy 5Y-8R is an agent with American Intelligence.
That really seems to sum up rather completely what we know about his work. It definitely looks like he works for America but that is not certain. He reports to headquarters somewhere but whose HQ is never mentioned. Is he in military intelligence as so many in his day were who had their exploits told in comic book format? Did he work for some known agency (well, at the time there were no known such groups except the FBI and the Secret Service)?
There is just far too little to go on.
What is 5Y-8R's real name? That, too, might or might not be a mystery. In the second adventure while undercover he tells a co-worker, who turns out to be on the "other side", that his name was Don Berry but it at first seems likely not real especially when he adds that his friends call him Huckle. At the end of the adventure, though, his boss addresses him by that last name so ....
The tiny bit of data we can glean from his adventures show he is intrepid (no surprise there), resourceful and determined. He is also athletic enough to handle himself in fist fights and to leap off a speeding and careening motorcycle onto the hood of an enemy motorcar. So add agile to the mix.
Also toss in he knows his way around the water and he can ride a motorcycle pretty well.
That our 5Y-8R in a very tiny nutshell. Or, as I implied earlier, it is our two Super Spy agents at work. It is hard to say and not really that important since after the second adventure, he (or they) was never heard from again.