Why is water called "the universal solvent" and why is this important for living things?

H2O or water is used by all living organisms wether it is plants dogs or even people

As it dissolves a large number of solid, liquid and gaseous substances it's called a universal solvent. It's important for living thing because all of them depend on water to survive. For example, many organisms live in the water and they find some of the nutrients that are necessary for live dissolved in water - gases included.