yes a pentagon is one of the polygons and it has 5 sides and a polygon can be made with all sides straight and they have to be all in a closed shape if it has a little bit of open space it is not a polygon
polygons:
Quadrilateral 4 sides
Pentagon 5 sides
Hexagon 6 sides
Octagon 8 sides
hepatgon 7 sides
Nonagon 9 sides
Decagon 10 sides
hope my answer is useful!