Theory:

In a few cases, there can be two or more lines of symmetry.
 
Consider the following figure:
 
1(1).png
 
The final figure will look like this:
 
2(1).png
 
A square has four equal sides. So it is a regular polygon.
 
A square has \(4\) lines of symmetry.
 
In case of regular polygons, the number of lines of symmetry equals the number of sides.
 
A polygon:
If three or more line segments form a closed surface, then it is a polygon. The line segment can be of any length.
Regular polygon:
If three or more line segments of equal length form a closed surface, then it is called a regular polygon. Equilateral triangle, square, pentagon and hexagon are a few examples of regular polygon.
Let us look at a few more examples.
 
Shape
Number of sides
Lines of symmetry
Final figure
5(1).png
\(3\)
3.png
4(1).png
8(1).png
\(5\)
7(1).png
6(1).png
11(1).png
\(6\)
9(1).png
10(1).png