If I understand what you ae asking, you are saying that there are two labels on each key and you want to know how to access each function.
One of the labels on each key should be a different color and there should also be a different key with only a label of that color. That one key must be pressed with the other key to do the second function.
For example my laptop has the second function of the key in purple. The F3 key has F3 printed on it in white and a quarter moon in purple (which stands for sleep). Many of the keys, not just the function keys, are like this. There is also a key that only has a Fn on it in purple. If you hold down on the Fn key and press one of the other keys with a purple label on it, the key will do the puple label function and not the white label. Pressing the key without pressing the Fn key will do the white label function.