the .75 means multiply the time by .75
for example: a unit takes 8 seconds to train normally, so it takes 6 seconds to train after the upgrade is researched.
8 seconds x .75 = 6 seconds
A Halo Wars Story: Once upon a time, there was a light bridge. On that light bridge, there were many covenant. When the UNSC turned the bridge off, the covenant fell. The End.