Thanks it helped me figure out what rooting did and now I know its not for me (unless in dire need) to use
DO look at unlocking your bootloader ASAP when you get your phone. Why? Unlocking the bootloader is needed if you
ever want to mod your phone for any reason at any point in the future... AND it wipes your data. Better to prepare ahead and also to do the mandatory wipe before you have a lot of data on board.
Now to give my answer to the original question, "...
explain what rooting your phone does and is pros and cons?"
Rooting gives you control over your phone. It also will force you to do a lot of study on how to root, how Android works and specifics about your device. IMHO, knowledge and control are a good thing - IF you practice your due diligence and learn what you need to know. Otherwise, if you go about it in a lazy way, you can really Bork your device.
One of the biggest Pros is customizing your device and how it behaves. It will start to work in ways it might not out of the box, but you wish it would. You can add functionality and utility. You can extend battery life. You can eliminate needless bloat from firmware and carrierware. The freshness of new ideas can help keep you from getting bored with your phone and extend its service life. For certain OEM devices it may be that you can only get that next version of Android you want by flashing a custom ROM as the OEM no longer updates your device. In the Android world it happens all too often that a device (especially at less than the flagship level) only gets one or two incremental updates and never a whole new version. Search the forums and see how many threads there are of people crying, "
Why Doesn't Whosama Update My Whatsis to X.Y.Z??? I Need Dis!!!"
The secret Pro is that you learn. You study. You understand your device better and also better understand what you want out of it... And what you want in your next device.
The Cons? Flashing can be addictive. When taken to an extreme it can cause dissatisfaction with your device; but that is mostly from choosing the wrong device to begin with. It can reveal flaws or weaknesses in your device you had no idea were there when you were a newbie just learning what mobile is and can do.
It can also be dangerous for your device. Some devices are more open and easier to mod. Some are more prone to being locked and some are straight up impossible (or nearly so) to hack into. The risk of Borking your device varies as widely as the choice of devices...
I would suggest that if you believe even remotely that you might at some time want or need to mod your device you add the ease of doing so into researching which device to get. Good luck to you (and future readers of this thread needing similar advice).