rooting my phone S4 SGH-I337 done it before but....

I understand the rooting process more or less. What I do not understand is why my Galaxy S4 SGH-I337 has a Baseband ver ending in NJ5. I'm running Kitkat 4.4.4 Should I not have Bb ver ending in NJ4? What will this mean if i root and try to install Lollipop. Thanks and please feel free to push me to the correct forum, I am not sure where to ask this