The ratio is the relationship of two numbers. Here is an example, you have 2 apples and 6 bananas. To compare the ratio between the apples and the bananas we create a ratio, so the ratio would be 2 to 6, or 2:6, or 2/6.
A rate is a little different than the ratio, it is a special kind of ratio. That is a comparison of measurements that have different units, like pounds and quarters.