Complex sentence: The direct method of teaching, which is sometimes called the "natural method", and is often (but not exclusively) used in teaching foreign languages, refrains from using the learners' native language and uses only the target language.
Split into simpler sentences: The direct method of teaching, sometimes called the "natural method". Not limited to but often used in teaching foreign languages, the method refrains from using the learners' native language and uses only the target language.