The reaction represent the COMBUSTION OF METHANE.
A combustion reaction is said to occur when an hydrocarbon react with oxygen to produce carbon dioxide and water. The chemical equation given above shows the interaction between methane [which is an hydrocarbon] and oxygen; the products are carbon dioxide and water, this shows that the reaction is a combustion reaction. During the course of the reaction, the chemical bonds in oxygen and methane get broken down and they re-arrange to yield the products; energy is given off in the course of the reaction.