YOU SAID:

This is hard to understand

INTO JAPANESE

これは理解するのが難しいです

BACK INTO ENGLISH

This is difficult to understand

INTO JAPANESE

この本は難しすぎて理解できない。

BACK INTO ENGLISH

This book is too difficult to understand.

INTO JAPANESE

この本は難しすぎて理解できない。

BACK INTO ENGLISH

This book is too difficult to understand.