For unpolarized light electric vector associated with light, is oscillating randomly in all directions in a plane perpendicular to the direction of propagation of light.
In linearly polarised light oscillating electric vector gets aligned along one direction perpendicular to the direction of propagation of light.
[Under the influence of the electric field of the incident wave, the electrons of the scattering molecules, accelerated parallel to the double arrows, do not radiate energy towards the observer. Hence, the scattered light gets polarized.]
