Answer: It means there is an end to everything, nothing is permanent and nothing is forever.
Explanation: Every single living organism has a beginning and an end, it's only a matter of time. Just like the day we were born; we will surely die one day and every single riches and fortunes we have saved up becomes meaningless to us (the dead don't use money), Only our kind heartedness, our charity and everything good we did during our lifetime becomes valuable to us, all other things are vanity and meaningless.
Yes you can because dreams are dreams.
The meaning is that being positive will get to a lot more places and you will get more things being positive. If ur negative all the time u will amount to nothing.