There are many possible answers but the most likely one, for your level, is a triangular prism.
A pyramid
A square pyramid
Each of them has four triangular faces.
None, because there can be no such thing as a triangular square. If it is triangular it cannot be a square, if it is a square it cannot be triangular.
Triangular based pyramid
A pyramid
A square pyramid
a square pyramid (i found it in my sons math book !)
Triangular prism
A triangular prism.
A triangular prism.
A triangular prism has 2 triangular faces and 3 rectangular faces.
triangular pyramid
Four triangular faces.
A triangular prism.
A Triangular Prism
Each of them has four triangular faces.