it's a pyramid with 5 sides.
A square pyramid.
All except the base are always triangles; the shape of the base gives the name to the pyramid; eg a pentagonal pyramid has a pentagon as the base and five triangular faces; a triangular pyramid has three triangular faces and also has a triangle for the base.
A pyramid with an irregular pentagon base.
It is a pyramid
That would be a triangular pyramid.
A triangular prism can have a square or triangular base, but faces are normally triangles. (I think)