I believe most people have heard this before.
Why action speaks louder than words?

Because usually people knew how to say certain things but they never do it.

For example, when it comes to serving God, many people say “I want to serve God; I want to do this and that for God”. We can speak about it but our actions must show it out as well to really mean we want to serve God.

Another example is...

If you want to do well in your exams everyone can say that but they do not study hard,

You can’t just stare at your own textbook and daydream that you score A’s. You got to do something like reading it, understanding it in order to score well in your exams! We should also pray to God. With prayer and works(actions) surely you will score well.

Matthew 8:26 says,
But He said to them, "Why are you fearful, O you of little faith?" Then He arose and rebuked the winds and the sea, and there was a great calm.

This verse is saying that you got to have faith and act out and not just by speaking.It says “then he arose and rebuked the winds and the sea, and there was a great calm. God didn’t just look at the situation and not doing anything, instead, God solve it by rebuking the winds and the sea and everything became calm.

Let’s all remember that ' actions speak louder than words! '. :D