What does " Steps" mean when bending on a guitar?

Im learning how to play walk by pantera and some songs by black label society, we all know dime and zakk love to do bends after like two notes lol, anyways my question is, it's telling me for the initial riff to bend almost half a step or something like that, what does it mean by step? And also, what is the tune for 1 1/4 step down?