In the simplest of terms...2 hormones responsible for fertility.
FSH........keeps the ovaries intact and the eggs healthy.
LH produces ovulation...the egg passes from the ovary into the tube on it's way to the uterus.
Both of these hormones have to be present to stand any chance of fertilisation.
Don't worry about the units of measurement:
FSH needs to be between 2-----20 throughout the cycle.
LH....needs to be between less than 7 but greater than 20 on day of ovulation.
You live in Spain...the units may be different.