These three phrases show that Pew is being frightened by the sound of the horses coming closer. So, when he quickly dashes away, he is most likely running out of fear. When he "turned with a scream" it shows that Pew was horrified by the thought that the riders on the horses were going to catch up to him. He is screaming out of terror.
This poem is about our tongue, how it can cause trouble and make peace, how it can help build someone up or how it could destroy someone's moral forever.
