SPH in the OS cylinder column means sphere power. If there is a signs of "SPH" cylinder, it stands for you have no astigmatic correction in the particular eye. That is why there is nothing filled out in the axis column. If you have astigmatism in the particular eye, thus the cylinder and the axis columns would be filled out.
SPH is one of the parameters to report your eye prescription. Your sph +4.00 means that the concave sphere with no astigmatism belongs to the hyperopia 400 prescription. However, there are other parameters, such as CYL which means the astigmatism part and AX which means the axis position in the astigmatism.