It is better to grow plants in soil than in sand because soil

Soil has the minerals and nutrients that the plate needs while the sand has little to no minerals and nutrients

Plants grow MUCH better in soil than sand. This is because, unlike soil, sand does not have any humus (organic carbon compounds) and so does not hold water and nutrients. It is the humus that gives soils their crumb-like structure of air pockets and which also absorbs water and nutrients. Sand alone does not hold water for any length of time.