Most schools and education organizations that advertise on our job board will ask you to have either a teaching license and/or an ESL certification, such as TEFL. (While others will only ask you to hold a bachelor's degree.)
A "teaching license" refers to the teaching credential that allows you to legally work as a teacher within a given area (i.e. your home country). A certified teacher has a recognized teaching qualification or license awarded by an education board or local governing body.
A "teaching license" can also be referred to as a "teaching certification", "qualification" or "credential", depending on where you qualified as a teacher.
Although it qualifies you to teach in many countries, an ESL certification is not considered a teaching license.