Macbook pro's latest version of OS system

Hi! I purchased a Macbook Pro Retina (2017 model) 13" (screen) laptop, with Core i7, 16Gb RAM, SSD 512GB.

How can I check what version is the O/S in my Macbook Pro? What are the latest 3 OS version available? I want to have the latest OS, running in my laptop.

So how do I know that I have the latest, if not the latest 3 OS version in my laptop.

If not what are the "availble"

I would like to find out if I can upgrade to the latest OS version or at least up to the latest 2 OS version. Can the specs of my Macbook Pro laptop be able to utilize the latest 2 or 3 OS versions? How can I also check & find out what OS version is running in my laptop. I also plan to get Microsoft (MS) Office. Per check, the specifications for my Macbook Pro require to be at least the last 3 versions of its OS. Otherwise, the MS Office may not work with my laptop. Appreciate inputs / feedback, thanks!