Materials with high heat capacities require a lot of heat to be stored up before a small change. Materials with low heat capacities require very little heat to be stored up before a large change.
The heat capacity of one gram (or some other unit of mass) of a material is called the specific heat capacity of the material, so that the heat capacity of something is its mass times its specific heat capacity.
Specific heat capacities are often listed in tables, like this one: 
Heat capacity Facts for Kids. Kiddle Encyclopedia.