A Non-Disclosure Agreement is a contract used to maintain privacy in agreements where sensitive information is exchanged between two parties. This NDA has been designed to protect both parties. If you want a Non Disclosure Agreement that only protects one party, you can find it here.
Ultimately, an NDA is designed to prevent someone from disclosing information you have shared with them with the intention of keeping the information secret.
More information regarding Non-Disclosure agreements generally can be found here.