A uniform Electric field is directed parallel to and in the direction of the positive x-axis.
A proton is placed some where in the x y plane.
Since, a proton is positively charged, the force on it due to the field
will be in the direction parallel to x - axis , from the point where the proton is placed.
e = q = electric charge of a proton
So direction of Force is same as the direction of electric field.