There are a few type of symmetry your might need to know about.
This is really easy. You just draw a dotted line along where a shape will fold exactly.
A regular polygon has as many lines of symmetry as its number of sides.Rotational Symmetry
This is how many times you can rotate a shape to fit back into itself. Again regular polygons have the same order of rotational symmetry as their number of sides.
If a shape tessellates it fits together without any gaps.
Regular polygons tessellate if their interior angles divide into 360° exactly.