Here we show an elctromagnetic wave coming at you. The electric field is shown in red, and the magnetic field in green. Both fields are shown along a line through the middle of the cube, the direction of propagation. For the center point of the front face, you can see the E-field and B-field oscillation in time quite easily. Since this is a plane wave, all points on the front face have the same phases for their E- and B-fields.