Final answer:
The phrase 'Cabeza de Vaca and his men' is an appositive phrase renaming the subject of the sentence.
Step-by-step explanation:
The phrase 'Cabeza de Vaca and his men' is an appositive phrase renaming the subject of the sentence. It provides additional information about the subject but is not essential to the meaning of the sentence. In this case, the appositive phrase is highlighting the individuals who traveled about 10,000 miles during their journey.