condensed matter - What is a $p_x + i p_y$ superconductor? Relation to topological superconductors

I often read about s-wave and p-wave superconductors. In particular a $p_x + i p_y$ superconductor - often mentioned in combination with topological superconductors.

I understand that the overall Cooper pair wavefunction may have orbital angular momentum = 0 (s-wave) or orbital angular momentum = 1 (p-wave) where the first one is spherically symmetric.

Now what does the splitting in a real ($p_x$) and imaginary ($p_y$) part mean? Why is it written in this form and why is that important (e.g. for zero Majorana modes) ?