Looking a little closer at the logo, the "A" IN Z-A might actually be the Greek letter Lambda. Which meaning of Lambda they're going for is hard to tell. It has connections to the expansion of the universe, subatomic particles, light, calculations for asteroids hitting the Earth, computer memory, and military matters. The lower case version is also the Half-Life logo, so maybe there's some hint there? It's a little interesting given Guzzlord's apocalyptic alternate timeline in USUM. As well was Deoxy's meteor likely being the source of Mega Evolution.
But, if we think of the title as "Zeta Lambda" instead, maybe that means something more specific that my googling isn't leading me to? Other than sounding like a fraternity. Both letters seem to have ties to the unsolved Riemann Hypothesis. Which is....complicated. But, basically solving the Riemann Hypothesis would mean solving a bunch of other mathematical theorems since a lot of calculations assume that it is true. What that means....I dunno? Something about repeating patterns, maybe?
It also looks a lot like the symbol from Stargate, but that's probably a coincidence.
But, you pronounce the letter Lambda like the letter L. So the title reads...Zill. Which is...a type of finger-cymbal used in belly dancing. Yeah, okay, I don't know what the title means.