There was a content fee charged on my line, what is this for?
Unless you can provide more information, there is no way for anyone on this forum to respond with an accurate answer.
How much was the charge? What was the description of the charge. Have you googled the description of the charge preceded with the word "Verizon"? For example, the first result when I googled "Verizon safe wifi" as the information provided by @tmiller3811 was where I got the answer for that inquiry.