Original: To render the meaning of the Greek intensive verb, the early Latin translators of the New Testament, who had no corresponding verb in their language, felt the need to use the phrase "gratia plena" (full of grace).
Simplified: The form of the verb is intensive, so we know the translation is "full of grace". To show the meaning of the Greek intensive verb, the early Latin translators of the New Testament, who didn't have a word in Latin with the same meaning,used the phrase "gratia plena" (full of grace).