I’ll try to explain it, but I’m not sure it will be “simpler”. The paragraph means:
When I write my thesis (to obtain my doctor's degree), I learned things which I never knew before. First, it is possible to live even though all you have to eat are bananas, and all you have to drink is coffee. Second, you can get enough water in your body if drink vodka or wine. Also, I don't want to frighten you, but I noticed that there is a bright light in the sky, and I want someone to explain to me what it is.
The paragraph is intended as a joke. A person who writes a thesis normally learns a lot of things about the subject of her thesis. However, this person didn't learn anything about the subject of her thesis. All she learned was that she could survive by eating bananas and drinking coffee only; and that she could hydrate herself (get enough water in her body) by drinking vodka and wine. The humor is based on the fact that SHE WAS SO BUSY WRITING HER THESIS that she couldn't take time to eat a decent meal. Also, she had to stay inside day and night to write it. Therefore, when she finally finished writing her thesis and went outside, she was surprised to see a bright light in the sky – which, of course, was the sun!