You’ll be randomly paired with a partner who’s online and using the feature. Over a 90-second period, you and your partner will be shown the same set of images and asked to provide as many labels as possible to describe each image you see. When your label matches your partner’s label, you’ll earn some points and move on to the next image until time runs out.
You DO get awarded points though!
Although you do not have to log in to your Google account to help, logging in will allow you to keep track of your points.
That makes it all worthwhile.