A psalm is a special kind of poem or song that people use to talk to God. A communal lament is a type of psalm where a group of people get together to talk to God about something sad or scary that is happening in their community.
Let's say there is a big storm and it floods the town. The people might feel really scared and worried about what is going to happen next. They might get together in a church or a community center and sing a psalm of communal lament to talk to God about their feelings.
The psalm might say things like "God, we are really scared and we don't know what to do" or "please help us because we feel like everything is falling apart". The people might also sing about how they know God is powerful and can help them through this difficult time.
By singing a psalm of communal lament together, the people are able to share their feelings with each other and feel like they are not alone. They also feel like God is listening and will help them through the hard times.