The Greek meaning of biblical words is important when studying the Bible because words in the original Greek can have different meanings than the English translation. Understanding the words used in the original language allows for a deeper understanding of the intended messages in the Bible.
Translations are rarely perfect in their ability to convey exact messages from one language to another. For example, while English verbs have tenses, Greek verbs have tenses as well as aspects. When a Greek word is written in present tense, it can also mean that the action taking place is occurring repeatedly or constantly.
This becomes important when specific instructions in the Bible lose part of their meaning when translated into English. One example of this appears in Ephesians 5:18, where Paul instructs the Ephesians to "be filled with the Spirit." In the original Greek, the verb used means "to be continuously filled" with the Spirit, but when translated to English the aspect is lost.
Another important reason to study the original Greek words is to gain a greater understanding of controversial pieces of Scripture. This can help protect against faulty teaching by others, who may interpret Scripture inaccurately or preach a message that is different from the original for unethical reasons.
Being aware of the original Greek also makes it possible to determine which translation of the New Testament is the most accurate version. When the meaning of the original Greek is known, it is much easier to decipher which of the modern translations does the best job of accurately portraying the original words.