What does it mean to have a large specific heat capacity?

There is a property called specific heat capacity that describes the amount of heat required to raise the temperature of the substance by #1^@ "C"#.

Water happens to have one of the highest specific heat capacities for any liquid, at #"4.184 J/g"^@ "C"#. That means it absorbs a large amount of heat per #""^@ "C"# of increase in temperature.

You can see a list of some specific heat capacities here:
http://www2.ucdsb.on.ca/tiss/stretton/database/Specific_Heat_Capacity_Table.html

Let's take water (#c = "4.184 J/g"^@"C"#) and compare it to copper solid (#c = "0.385 J/g"^@"C"#).

We will be using this equation, which relates heat transfer #q# to mass #m#, specific heat capacity #c#, and the change in temperature #DeltaT#:

#\mathbf(q = mcDeltaT)#

Adding #"1000 J"# of heat to #"100 g"# of each substance, we get:

WATER

#q = m_("H"_2"O")c_("H"_2"O")DeltaT#

#"1000 J" = ("100 g")("4.184 J/g"^@"C")DeltaT#

#DeltaT = (1000 cancel"J")/((100 cancel"g")("4.184" cancel"J""/"cancel"g"^@"C"))#

#~~ color(blue)(2.390^@ "C")#

COPPER

#q = m_"Cu"c_"Cu"DeltaT#

#"1000 J" = ("100 g")("0.385 J/g"^@"C")DeltaT#

#DeltaT = (1000 cancel"J")/((100 cancel"g")("0.385" cancel"J""/"cancel"g"^@"C"))#

#~~ color(blue)(25.97^@ "C")#

The difference is clear:

The higher the specific heat capacity, the smaller the temperature change for the same amount of heat applied to the same mass of substance.