High School Honies What Dictionaries Are Suitable For High School Students That Is Easy To Understand?

What dictionaries are suitable for high school students that is easy to understand? - high school honies

I go to school next year (after 7 years in Australia) and I want to know if there are dictionaries for students. The dictionaries are dictionaries that Junior and I have not many words that are used in the school.

So, what dictionaries are for secondary students use?