It can be "Du siehst" (informally addressing), "Ihr seht" or "Sie sehen" (formally addressing)
so what exactly is the differnce between "Ihr seht das brot" and "Du siehst das Brot"? I am not understanding this.
"Ihr seht das Brot" - informally addressed group and "Du siehst das Brot" - informally addressed single person
this part is confusing i mean i don't know when to use ihr and when to use du
You use “du” if you are talking informally to just one person. If you are talking (still informally) to more than one person (you all), you use “ihr”.
Why can't I use "den Brot" instead of "das Brot"?
Den is the accusative of masculine nominative der. The feminine and neuter articles don't change. Direct object or subject, the bread will always be "das Brot".