This proverb means that a friend will always be there, no matter what situation you're in. It is a friend that always stays by you're side. These are the kind of people you can trust and rely on. These are the kind of people you want around you, not the people that leave when trouble arises. This kind of friend is called a fair-weather friend. This proverb doesn't just mean help as in a task, but help in every other way, mentally, economically, etc. So in conclusion this is true friendship.
