You gain the ability to Airbend which can be used to manipulate Air, the element of freedom, starting with only knowledge of the basics but holding prodigious talent, enough to become a master Airbender on your own and even invent new Airbending styles and applications like assisted flight through the use of a glider or flightsuit.
Airbending is a deeply spiritual discipline, and as such necessitates constant spiritual awareness which will result in the deterioration of your airbending capabilities if such is not adheered to.