What does reboot and flat line mean?

Here is a link to the glossary page: https://www.nofap.com/glossary/

Flat line is the temporary loss of libido. It can last a few days or weeks. Some people experience it right away and some feel it after the initial detox period. At the start of our reboot our brain and body chemicals and hormones are out of balance. During our reboot our bodies are trying to balance themselves out and this can have different effects on the way we think or feel. Even though someone can be experiencing a physical flatline they can still be triggered by external things - physical, emotional, mental, or environmental triggers.

Reboot is a term that describes the process of returning your brain back to a normal condition. The brain is incredibly resilient and malleable. We have abused it and shaped it a way that has makes us miserable. The length of time it takes to return to a more normal-like condition varies from person to person. The term is also a little misleading because we are addicts and we will always be capable of addictive behavior. But by going through a detox period and learning to cope with life in healthier ways it becomes possible to lead a normal, healthy life again.