Imagine you go to the beach and try to catch a big wave and put it in your backpack. You can't, right? All the water leaks out! Or you try to close your hand really fast to trap the wind. Impossible! The Bible says this to remind us that we're really small, and that our Father in Heaven is very, very big and powerful.
The proverb asks a question: "Who can command the sea and the wind? Who is his son?" We know the answer! It's King Jesus! One day he was in a little boat, the storm was really scary, and he just said: "Be still, wind!" And the wind obeyed right away.
So, when you're scared of the dark or of something hard, remember your best friend is the Owner of the wind and the sea!