It's only referring to BRICS. You are looking at nominal GDP, and not Purchasing Power Adjusted (PPP). If a dollar goes twice as far in China, then their nominal GDP would need to be doubled to get the "real" comparable value. That's what PPP is.
I thought it was the other way around? Nominal was supposed to be better for comparing overall economic heft among countries, while PPP is better for internal measures and comparisons in living standards (GDP PPP per capita for example)?
You are correct - PPP is how many Big Macs you can buy (the Big Mac Index) in a country, Nominal GDP is how many nuclear submarines you can buy