Mark Twain
In most cases, actions indeed speak louder than words but not most of the time, as Mark Twain said in his quote above. There are still instances when we need words. An action alone is not enough. Actions and words blend in together.
But what if it is only pure words... no action?
Let's admit, we've been hearing this idiom for the rest of our lives. In schools, we often hear "Action speaks louder than words". In our homes, we hear it from our family, as well as from our friends.
Anyway, what does the idiom "Actions speak louder than words" exactly mean?
Let's have this definition from thefreedictionary.com:
Actions speak louder than words means what you do is more important than what you say.
Agree? Or do you have another definition for the said phrase?

In this world, words alone is not enough. If you really mean what you said, show it. But remember that life is not also only about actions. You also need some words. They blend in together. Without the other, the other is not complete. Agree?