A cone is a geometric shape. If we "build" it, it may be easier to understand what it is. Start with a plane and put a circle in it. Now pick a point that is "above" the plane, and draw a line from the point to the circumference of the circle. Now draw another one. And another. If you draw all the lines from that point to the circle, you'll create a cone.
If you picked a point that is on a line perpendicular to the plane and that goes through the center of the circle, then you have set the conditions to make a right circular cone. This 3-dimentional geometric figure is fun to investigate. Use the link below to lean more about the cone.