What causes coastal fog and heavy mist at the beach

And could you explain as if I know just about nothing about weather.

In the west coast in the United States, the main cause is due to he cold eastern Pacific ocean waters.The colder water temperatures will result in a cool and moist layer of air to form near the surface. When you have colder air near the surface and warmer air above it, you will have a stable environment. During the warm season, this layer can get very stable. This layer is known as the marine layer.

Because this layer is so stable, the cool and moist air will be stuck near the surface and can not mix with the drier and warmer air aloft. With this layer being so moist, a deck of low coastal clouds will usually form along the coast. Where the base of the low clouds meets the ground surface is where you will find the thick to dense coastal fog and and patchy areas of heavy mist.

Warm air over the ocean being cooled below the dew point by cool ocean temperatures and moving inland.