Answer:
Explanation: What William Bradford might have meant by the quote is (in step-by-step or sentence-by-sentence manner):
# The Mayflower Saints and their descendants have always believed that they and they alone are special people from God, sent as a light to other Christians.
# Bradford defined the power of a beacon in the first half of the second sentence
# Bradford, in the second half of the second sentence, likened the influence of the Mayflower Saints to the power of a beacon
# "so the light (godly power of the Mayflower Saints) here kindled hath shone (influenced many people) to many, yea in some sort to our whole nation (evidence of the largeness of the number of people the godly power of the Mayflower Saints reached)"