You can copy text by using the y (yank) command, followed by a movement or a text object. You can also hit y from a visual mode when you have selected some text.
Let's yank the following piece of code by typing ye (yank until the end of the word):
This will copy animal_kind into our default register. Now, place the cursor where you want the text to appear (the text is inserted after the cursor):
To paste the ...