At the top of the Browse area is the menu item 'Select' which leads to these choices:
'Return' will cancel the choice.Word Line Sentence Verse Paragraph File Return
The others put you in 'select mode' where
the cursor changes to a question mark.
Move to a word you are interested in selecting
and pause over it. The selected area around that word
will be highlighted in red temporarily.
Selecting a sentence may not always give you what you expect.
Determining where a sentence begins and ends is not an exact science.

The contents of the selected area will
be put in the message area. This enables you
to copy the selected text from files, books, and email
for including in email or for inserting in other files.
Another effect of making a selection is that the text will be put on the clipboard. You can then paste it into other applications. Any text that is 'cleared' will also be put on the clipboard.