*I AM NOT A TEACHER OR NATIVE.*
There are some markets/websites/... in which photographers could offer their works for sale. For example, in shutterstock.com you, as a photographer, can upload even thousands of your works. Then, the more people download your stock photos, the more you will be paid by the website. For instance, in Shutterstock.com you will be paid 25c for any single download. Hence, 1000 downloads means 25c * 1000 = 25000 cents = $250 ).
In my opinion, the red statement refers to the very low price of the photographs in such markets which results in very low income for the photographer.
Student or Learner