ThyUnknownSaint Basically what he/she means is that if you sign a contract with Qidian, they'll protect the IP for you. They have to, because the rights to your story and your IP now legally belongs to Qidian, not you. If someone copies/plagiarizes your work and sells it for a profit, Qidian will sue the guy and handle all the lawsuits. You don't have to worry about suing people or trying to protect your IP because Qidian will do it for you.
However, if you don't have a contract, then you still own your IP. It's still exclusive to you, you're the only holder of your IP. This means that if someone copies/plagiarizes your work and sells it for a profit, you'll have to track him or her down yourself, you'll have to take the initiative to sue him/her and handle all the lawsuits/legalities yourself. You'll have to hire your own lawyer as opposed to Qidian already having a legal team to do it for you (and them).