The above each ingredient tells you the suggested minimum and maximum ingredient levels. These levels are based on the ratios between the amount of one ingredient and every other ingredient, as learned from the recipe templates listed below. If you fall out of this range, or a will point the way back.
Sometimes, you'll see a next to an ingredient. This means other ingredients need to be adjusted in order to bring this ingredient back in range. Disable the effect of an ingredient on others by clicking on its blue bar.
Read more here, or see how some common ingredients affect the taste of chocolate chip cookies here.