Let's break it down:
* Tu: You (informal, singular)
* you: This is a bit redundant and is often used to emphasize the feeling of suffering
* fais: present tense of "faire" (to do, to make)
* souffrir: to suffer
The phrase expresses a strong feeling of pain or discomfort caused by the person being addressed. It can be used in a variety of contexts, from a romantic relationship to a friendship to a family situation.