It is the vertex at which all the triangular faces meet.
A triangular prism.
The 3-D shape that has 4 faces is the tetrahedron. All of its faces are triangular, and they all converge at a single vertex.
The description given fits to that of a pyramid
A tetrahedron (4 faces) or triangular bipyramid (5 faces).
A geometric figure with a polygonal base and triangular sides is called a pyramid.
A polygonal pyramid.
A triangular based pyramid would seem to fit the given description
a polygonal prism or a polygond
no, it's a pyramid