In Zed's bio, it said that she is age 134 ESY/29 MSY but what does it stand for?

An excellent question! 

You may have noted that in her bio it states that she is Mezari, but hails from a colony planet called Ezes in the Biotos constellation.

Ezes is a planet that orbits close to a relatively cool star compared to Mezan, which in turn is farther out from a relatively hot star. For that reason, her age in "Ezes Standard Years" is much greater than her age in "Mezan Standard Years". That explains the difference in the two numbers. 

This sort of astronomical complexity, combined with the expansion of the universe and the interactions of gravity and time, makes accurate timekeeping a real pain in the neck.

-Slow

Thank you, but does the Endless universe have like a galactic standard time? Like in Mass effect?