This refers to materials or courses which are designed around a series of authentic tasks which give the learner experience of using the language in ways in which it is used in the real world outside the classroom.
They usually have no predetermined language syllabus and the aim is for learners to learn from the tasks the language that they need for successful participation in them.
Examples of such task would be working out the itinerary of a journey from a timetable, completing a passport application form ordering a product from a catalogue and giving directions to the post office.