Hebrews is a Bible book, in the New Testament.
The Book of Hebrews teaches many things about Jesus. We do not know the author of Hebrews. Some people think that Paul wrote Hebrews.
The Book of Hebrews is an important book that teaches many lessons about the Bible. The Book of Hebrews teaches that Jesus was not an angel (a servant of God from heaven) (Hebrews 1). Jesus is God. But Jesus became a man. Jesus is our priest (Hebrews chapters 5-9). And Jesus is the perfect priest (Hebrews 7:25-28). In the Old Testament, priests killed animals so that God would forgive the people. But Jesus died himself, to suffer the punishment for our evil deeds. God accepted Jesus's blood (that is, his death - Hebrews 9). So, God will forgive us when we trust Jesus.
In the Bible's Old Testament, many people trusted God (Hebrews 11). They believed that God would send Jesus. So, they were not afraid, although they had great troubles. So, we too should trust God when we have troubles (Hebrews 12:1-2).