“time can be an ally or an enemy. what it becomes depends entirely on you, your goals, and your determination to use every available minute” what does this quote mean and why does it matter?

It means that, well, let’s say you forgot to do homework and it’s due today. In that situation, it would be an enemy, because you really need to do it but you can’t, ‘cause you have to get ready. But maybe, it starts to rain really hard. You may have time to do it, and time would be an ally.

Time depends on you because if you do something you need to at first, it’ll be completed. But if you don’t, you’ll face the consequences.

Hope this helps! I’m kind of bad of explaining things so hopefully this makes sense.

The bell is just a signal that the set time of the end of class is passing. the teacher lets you know when it's okay to leave.

Manga is a japanese comic book (sort of) while anime is the a sort of show on a screen. most animes were originally manga though