Final answer:
An adjective clause is a dependent clause that functions as an adjective to modify a noun or pronoun in the main clause of a sentence. In the given sentence, 'that is a Spanish-speaking country' is an adjective clause that provides additional information about Peru.
Step-by-step explanation:
An adjective clause is a type of dependent clause that functions as an adjective to modify a noun or pronoun in the main clause of a sentence. It usually begins with a relative pronoun such as 'that', 'which', 'who', 'whom', or 'whose'. In the given sentence, the noun being modified is 'Peru', and the adjective clause is 'that is a Spanish-speaking country'. This clause provides additional information about Peru by describing it as a country where Spanish is spoken.