The Hebrew Bible, also known as the Old Testament, was written primarily in Hebrew, with some parts in Aramaic. It's like when you're texting a friend, and you switch between languages to express yourself better – the authors of the Hebrew Bible did the same thing. The Aramaic sections are like a special flavor added to the text, giving us a glimpse into the cultural context of the time.
The New Testament, on the other hand, was written mainly in Greek. This might seem surprising, but Greek was the common language of the Mediterranean world at that time, like English is today. Just as we use English to communicate with people from different countries, the authors of the New Testament used Greek to spread their message to a wider audience.