The zoom feature allows you to select larger or smaller chunks of text. By default, you will be most zoomed in when opening up a new text. That means that the text is highlighted word by word. However, if you zoom out, you can go through the text sentence by sentence. Finally, the most zoomed out feature allows you to select an entire paragraph.
Test out the Zoom Feature by pressing the "Zoom In" button and "Zoom Out" button on the same sentence