Imagine a round ball like a ball you play with. Now, let's try to imagine cutting little triangular pieces of paper and gluing them onto the ball. But we can’t just glue them anywhere, we need to make sure they all fit together without leaving any gaps.
When we finish gluing all these pieces we get a shape that looks like a ball but has flat surfaces on the sides, sort of like a cut-out ball. This shape is called a spherical polyhedron.
It is called "spherical" because it's made by putting flat pieces on a sphere (the round ball we started with) and it's called a "polyhedron" because it has many flat surfaces. Just like a cube or a pyramid are polyhedrons, this round shape with flat sides is also a polyhedron.
So, a spherical polyhedron is just a ball with lots of flat sides made by putting little flat triangles or other shapes all around it.