The teacher explains things in a way that's easy to understand.
Tips
usage
Almost always paired into the four-character set phrase 通俗易懂 ('popular and easy to understand') — used to praise plain, accessible writing or teaching. Standalone 易懂 also works, especially after 很 or 不: 不易懂 ('not easy to grasp').
grammar
易 + verb is a productive classical pattern: 易学 (easy to learn), 易记 (easy to remember), 易读 (easy to read). The opposite is 难 + verb: 难懂 (hard to understand), 难学 (hard to learn).
