Yuppp sure is hairgrass. Depending on tank size it will require med to high light. Isn't a nutrient hog but good substrate will help it to spread. For a quick lawn look good light/co2/ferts are the way to go
Whats your tank setup like? (size/lighting/filtration)
Not introducing any bottom feeders would for the first month or so would be best for the plant. Would give it time to spread its roots and anchor itself.