This Guaranty or Guarantee of Payment of Rent contract is an agreement between a guarantor for the tenant and the tenant's landlord. The guarantor agrees to pay the rent if the tenant is not able to pay. The guaranty contract sets out the details of this agreement, the trigger for the guarantor's payment, etc.
A guaranty is a contract under which one person agrees to pay a debt or perform a duty if the other person who is bound to pay the debt or perform the duty fails to do so. Usually, the party receiving the guaranty will first try to collect or obtain performance from the debtor before trying to collect from the one making the guaranty (guarantor).