No meaning at all, unless the teacher himself is called (سهل), then the phrase will mean (Teacher Sahl). Other than that, I cannot think of any other meaning in MSA.
The sentence is correct but makes no sense. An "easy going" teacher would make sense, how would you say that in Arabic? "A teacher that makes learning easy" is also a sentence that makes sense. How would you say that in English (a pedagogical teacher?) and Arabic?
@AnnaEE, an easy teacher who makes learning easy. Can be understood easily.
معلم سهل او معلمة سهلة