If you're new to networking entirely, you may want to start with basics and fundamentals like what Network+ offers before trying to wrap your head around NSX right out of the gate.
You are lucky to start with SDN - Software Defined Networking (NSX) and my recommendation is to start with some CCNA material to build your basics in Physical Networking skills
Start with the basics of networking with Jump start course & then with the CCNA.
Lot of basic stuffs are available in the Youtube videos to have the concepts cleared. Try to get some hands on the some of the network devices to understand how it works & play with it. If you have time & budget clear your CCNA first.
Once your basic concepts on networking is clear start with the NSX VCA6-NV. It will clear your basics.
Go through videos available on line. Its fun to learn NSX.