She is reading a book.
Meaning: This means that the person mentioned is looking at and trying to understand the words in a book. It's like saying, She's lost in the world of the story.
Choice of Words: Reading is a verb that means to look at and understand written or printed material. Book is a collection of written or printed pages bound together. When you put them together, "She is reading a book" tells us that the person mentioned is engaged in the activity of reading.
Alternative Expressions
Related Expressions