A proverb is a simple saying that expresses advice or general truth, based on experience and common sense. It is short, concrete and uses metaphorical language. Proverbs are generally considered to be wise sayings that guide us in the right path in our lives.
"Fortune favours the bold" is a proverb. It means being brave is always rewarded and one has to face his difficulties with courage. Being bold brings about good luck.
Reading or listening to long lectures may be boring. Proverbs are short sayings, that are to the point and easily get through to the reader/listener. Since the language is metaphorical, it is indirect, humorous and keeps the reader guessing. Proverbs have been adapted from various languages but it holds universal meaning. It explains good morals, ethics and values for all.