There's ozone, also called trioxygen, (O3), but I'm sure Hs wouldn't have to look that up. Do any other elements join in threes of their atoms?
I am tempted to ask if that is what's meant by triple element, but a) I believe O3 is classed as a molecule, and b) I don't think such things appear on the periodic table.
Googling doesn't yield anything for 'triple element' either.
I can only conclude that Hs is a very advanced chemist on the cusp of discoveries unknown to the rest of the world!