Is there a computer that can keep track of every human being on earth?
Yes. The context describes the largest computer on earth, reportedly located in Brussels, Belgium, dating from the 1960s, housed in a city-block-sized building, and capable of keeping track of every human being on earth. Though ancient, it was said to still be working.
Les explains that if supermarkets can track products to the last detail with scanners, then people should expect the same capability for every human being. He points back to the 1960s and the largest computer on earth, which he thinks is in Brussels, Belgium. It is ancient but was still working the last he heard. The building housing it is about a city block square, and that computer is very capable of keeping track of every human being on earth. He connects this to the mark of the beast as something common already: a number, an 18-digit number of 666. He also notes cashless society trials in America and Scandinavia, where communities could go 30 or 60 days without a checkbook or billfold. It worked, but checkout lines backed up because people could not find their cards and purses.