That’s a new word made up by someone (linguists) to mean “green-blue.” Apparently many groups don’t differentiate the color(s).
Read about it at Nature.
I wrote about the number of colors in a language varying, blue is green II, and language coloring vision earlier in my blogging career.
I keep coming back to it because I find it fascinating. But you can’t get the really cool article referenced in the last unless you’re a premium user of Nature online.