How is land cover related to land use?
They can both influence or even dictate the other.
Land cover (deciduous forest, grassland, urban area, bare soil, wetlands, water, etc.) affects how humans use the land. For example, we wouldn't arrive at an area marked as "urban" on a map and expect to harvest a large amount of timber. If harvesting timber is our goal, we would need to find land cover types related to forests.
Alternatively, the way we use the land impacts the land cover type. For example, if we arrive at a large area where the land cover is forest and we remove all of the trees, we change the land cover type from forest to bare soil or possibly grass.
Thus human uses of the land affect the land cover type but we also are affected in our use of the land by the land cover type.