The rock cycle is a cycle that rocks go through which involves melting, cooling, pressure, erosion, and other stages. Starting with a volcanic eruption, the lava turns into igneous rock, that can be melted into magma again, or can be crushed and pressed into other rocks beneath the crust to form metamorphic rock, or can be broken down by erosion and other factors. For the sake of it, let's say the rock got broken down, it turns into sediment that collects in areas and get layered and pressed, and layered, and pressed some more into a sedimentary rock. That rock can be broken down again, or melted, or pressed with heat and pressure. But let's say it went under the crust with other rocks, mixed with heat, pressure, and other types of rock to become metamorphic rock. Now let's say that metamorphic rock found it's way to a volcano, got melted, and erupted, and cooled to get back to a igneous rock. And the cycle never ends.
