Okay kiddo, so Isaiah 64 is a chapter in the Bible, which is a book that tells stories about God and his followers. In this chapter, the people who follow God are feeling really sad and upset because they think they've done something wrong and they're getting punished for it.
They're asking God to come down and help them out, because they feel like everything is falling apart and they don't know what to do. They're saying things like "Oh, God, that you would come down and make the mountains shake," because they want him to come and fix everything.
But they also know that they need to take responsibility for their actions, so they're saying sorry for the things they've done wrong and asking God to forgive them. They're asking him to remember that they're his people and that he loves them.
Basically, Isaiah 64 is all about asking for help and forgiveness from God when things are tough or when we've made mistakes. It shows that even when we feel really lost and sad, we can always turn to God for comfort and guidance.