In case you're being genuine, net neutrality is the concept that all internet traffics should be treated equally or neutrally. Such an attitude whether adopted through government regulation or industry self-regulation would mean that ISPs would not be able to discriminate between various types of traffic or to promote one service over another.
In practice, ISPs want neither net neutrality nor to be classified as public utility in order to promote their own services for things such as social media sites, video streaming services and much more. ISPs market this as "companies like Netflix should pay their fair share to use our infrastructure," however, Netflix already pays for its internet usage through companies such as Level-3 or its own infrastructure it has deployed.
Rather than having a "free lunch," companies already pay for the services they use. ISPs want to essentially triple-bill. They bill you, the consumer, for general internet access, then they want to charge an extra bill to services like Netflix; Facebook; Steam; etc., and finally, they want to charge you extra for using these services -- provided the companies aren't paying them extra to avoid doing so.
You can see an example of this in the mobile space, where certain services don't count toward your data usage. Future examples could be Comcast steering you toward its streaming service or AT&T steering you toward DirectTV Now.
The ultimate effect of a non-neutral internet is to discourage innovation because smaller companies can't compete with the added cost created by ISPs.
Edit: Political reasons for being against net neutrality are vague because it's driven primarily by industry lobbying. It can range from a general aversion to regulation, the aforementioned "free lunch" argument, and the bizarre idea that pricing smaller companies out of competition can actually increase competition and innovation.