The 2s orbital has one radial nodal surface, which is a spherical surface shown in Figure 1.
A nodal surface is where the electron probability density (and wave function) equals zero, meaning ψ2s(x)=0.
From the wave function graph in Figure 2, point B represents where the wave function crosses zero on the x-axis, indicating the location of the radial node.
Points A and C show maximum and minimum values respectively, while point D shows a non-zero region beyond the node.

