easy; simple; plain — easy to understand or expressed in straightforward language.
この本は平易な言葉で書かれている。
This book is written in plain, easy-to-understand language.
難しい説明を平易に言い換えてください。
Please rephrase the difficult explanation in simpler terms.
試験問題は平易だったので、合格者が多かった。
The exam questions were easy, so there were many passers.