Light can be represented as a transverse electromagnetic wave made up of mutually perpendicular, fluctuating electric and magnetic fields.
Here we have considered only the electric field vector but keep in mind that the magnetic field component behaves similarly. Light whose electric field oscillates in a single plane is said to be polarized.
Therefore light can be linearly polarized or circularly polarized. A combination of those two components results in the elliptical polarization, meaning that the electric field spirals with an elliptical cross-section.