The electric field lines are going away from the positive charge while the electric field lines are going towards the negative charge as shown below

The plane is conducting means it is made up of metal which has free electrons in it.

If now a positive charge (+q) is placed at a distance d from this plane, then it causes equivalent free electrons (-q) in the plane to get accumulated by attraction, at the side, where the positive charge is placed.

The other side of the plane will have equivalent positive charges (+q). This phenomenon is shown in the figure below

The electric field line is perpendicular to the plane according to the boundary conditions. The field at point P on the other side as shown in the figure above is directed perpendicular to the plane and always away from the plane.