Need help explaining the mindful breathing technique

Hello, please bear with my ignorance.

I've been meditation on and off for about 2 years, but never being seriously committed to it. I would lose motivation after a week or two. And I have never consulted online with techniques in doing it. Only now have I taken a dedication to being serious with it. Aside from my background, I have a question to ask.

I was wondering what this website (https://thebuddhistcentre.com/text/mindfulness-breathing) meant by step 2:

"In the second stage you subtly shift where you breathe, counting before the in-breath, anticipating the breath that is coming, but still counting from one to ten, and then starting again at one.

I don't really understand what they are trying to say by "subtly shifting where I breathe."

Also is it okay to keep my eyes open while I do mindful breathing exercises because when I close my eyes I tend to get sleepy.

Thanks!