An insurance release, also known as a settlement release, is a contract between you and the insurance company. The contract stipulates that the insurance company will offer you a compensatory amount in exchange for you releasing the insurance company from liability, i.e. dropping the claim against them or the party that they represent.
Signing an insurance release can be a good thing, but it can also be a risky thing as well. If you sign your insurance release and the settlement that you have been offered by the insurance company is much less than you really deserve, then you are forfeiting your right to pursue any further compensation.
You should never accept a first settlement offer or sign an insurance release on the first go-around. Often times, insurance companies low ball your claim by a significant amount in order to quickly make a profit off of you. If you do not negotiated for a higher amount, the insurance company will get away with this. It is always best to have an attorney thoroughly review a settlement contract before you sign it. If the contract is not within your best interest, an attorney can help you to negotiate for a higher amount, or can help you to pursue in-court litigation.
As a note, you should not sign anything for an insurance company without an attorney review first. This is not just limited to settlement releases; your insurance company may also ask you to sign other documents, such as a medical release document which gives the insurance company access to your medical history. Because your medical history may be used against you in some cases, you should not permit this.