Multi valued Relay Ratings
It gives current ratings at 3 AC voltages, and 1 DC voltage, each of those are listing certain maximums for certain markets, e.g. how much current it can handle at 120VAC would be important for america, 

This is how much current the relay coil can break at a given voltage without significantly reducing its lifetime estimation from the datasheet, DC is a much lower voltage because the arc does not self extinguish like with AC, 


277VAC - 10A
250VAC - 12A
120VAC - 15A
24VDC - 15A