This is the 4753rd most frequent Chinese word.
简
"简" means "simple" or "brief."
In this sentence, '简' is used as part of '简明' (clear, concise), describing the attribute of the book being succinct and easy to follow.
这本书的内容很简明易懂。
The content of this book is very clear and easy to understand.
Here, '简' appears in '简约' (minimalist), indicating simplicity and minimalism in the style of clothing.
她喜欢穿简约风格的衣服。
She likes wearing minimalist style clothing.
In this context, '简' is found in '简化字' (simplified characters), referring to the reduced complexity of Chinese characters for easier usage.