The number of lines of symmetry of a parallelogram depends on the type of parallelogram. A non-special parallelogram does not have any lines of symmetry. This includes any quadrilateral with two pairs of parallel and equal sides, except for rectangles, squares and rhombuses.
A rectangle is a parallelogram with four right angles. This property allows it to have two lines of symmetry.
A rhombus is a parallelogram with four equal sides. The number of lines of symmetry of a rhombus depends on whether it is a square or not. If it has four right angles, the rhombus is a square and thus has four lines of symmetry. If not, the rhombus only has two lines of symmetry.