If networking is relatively new to you, I highly recommend Ed Harmoush’s Practical Networking site (free). He has an index for CCNA level topics; this is the stuff you need to know (with the exception of EIGRP unless you are working with Cisco routers). Here is the CCNA index. And I recommend starting at the beginning; these are short and well prepared topics. He has some youtube videos that go along with some of his notes. For example the “how packets travel through a network” topic.
For easy to understand but technically correct VLAN info, I am not aware of any better than you will find there. If someone else knows someone that does a better job, please post it here. It’s not vendor specific, but since it is aimed at people studying for the Cisco CCNA, the examples are based on Cisco devices. But you should be able to follow along, because he explains as he does things.