How to understand what the browser sent to the server?

Question

Browsers

Let's say I upload a picture to toster.ru
In the developer panel, I see:

How can I see all the data that the browser sends to the server?
And most importantly, what and how many pictures? because I see some textual nonsense, but what it means - I do not understand.
Thank you.

Answer 1

Probably it's time to start studying the HTTP protocol documentation https://tools.ietf.org/html/rfc7540
in the screenshot, everything is according to the protocol...