It is definitely not a dumb question.
It is very important to understand the relevance of a focal point.
A circle is the set of all points equidistant from the central point.
An ellipse is the set of all points where the sum of the distance to each of the focal points stays constant.
So
A circle is an ellipse where the 2 foci are in the same spot.
Think of the way this guy draws the ellipse in the video below and you will see what I mean.
Here is how to draw one with two pins and a piece of string
https://youtu.be/Et3OdzEGX_w
Here is a great site that covers many important characteristics of ellipses.
There is a number of interactive pictures. Play with them make sure you understand what they are trying to demonstrate to you.
https://www.mathsisfun.com/geometry/ellipse.html