Imagine you are building a sandcastle on the beach. You make a little pile of sand and then you use a bucket of water to wet the sand so it becomes harder and easier to build with. As you keep building, the water keeps washing up on the sand and making it wet again.
Now imagine that the water keeps washing up on the sand over a long period of time, like years and years. This can happen because of things like changing weather patterns, rising sea levels or sinking land. As a result, the sand and other materials on the beach start to pile up higher and higher, forming what we call a "raised shoreline."
This raised shoreline can protect the land behind it from waves and flooding. It can also create new habitats for plants and animals that are adapted to living in a higher and drier environment. However, it's important to remember that raised shorelines aren't a permanent solution to sea-level rise, and we need to take action to reduce our impact on the environment and slow down the rate of global warming.