I'm doubly confused!
Firstly, when I go to Google, this is what I see
http://www.upl.co/uploads/Google-291554926251.jpg
I can only see one text box!
Secondly, I carry out dozens (if not hundreds) of Google searches each day but I never go anywhere near Google's home page. (Going there just now, to get the screenshot I've linked to above, is probably the first time I've seen that page in over a year).
Nearly all browsers have a search box at the top right, which saves you going to Google at all and/or entering your search string into the address bar (and then hitting 'Enter') will perform a similar function. With Firefox, users can choose to use either box; the one at the top right though allows you to search other sites (such as Amazon) as well.
If you insist upon going to Google's home page (WHY?) there's a possibility that your browser isn't displaying it properly. Try refreshing its cache:
https://www.refreshyourcache.com/en/home/
. . . but you'll probably find it far simpler just to use the search facility built into your browser.