An even function is a type of mathematical function that has the same value no matter which way it is "flipped". For example, if you had the number "2" and "flipped" it, it would still be 2. So if you had the function x^2 and wanted to "flip" it, it would still be x^2.
An odd function is a type of mathematical function that has the exact opposite value when it is "flipped". For example, if you had the number "-3" and "flipped" it, it would now be 3. So if you had the function 3x and wanted to "flip" it, it would now be -3x.