what is Rail to Rail supply?
Rail-to-rail means that the output of the op-amp can go all the way from V- to V+. Usually the output of non rail-to-rail op-amps can't reach negative or positive supply. For example if you apply a 5Vp-p sine wave to the AC-coupled input of a non rail-to-rail op-amp in unity gain configuration powered from +-2.5V, the output will be distorted (top and bottom of the waveform will be cut off). Some op-amps like LM358 are rated for "single supply operation". In practice this simply means that it's output can reach 0V when the negative supply is grounded.

Note that even if you ground the negative supply of the op-amp you might need to provide a virtual ground for the op-amp to operate correctly.