Answer:
Lines of symmetry are straight lines that divide a shape into two equal parts, where one part is an exact reflection or mirror image of the other. Therfore, a shape with 4 of these lines of symmetry would be a 2-dimensional square.
For Example:
If you have a 2-dimensional square, the 4 lines of symmetry would be vertical, horizontal, and 2 diagonal.
If you have a 2-dimensional rectangle, you would only have 2 lines of symmetry (vertical and horizontal).
If you have a 2-dimensional equilateral triangle, you would have 3 lines of symmetry (vertical and 2 diagonal).