Answers to such questions are better to be found elsewhere on the world wide web.
Briefly, the OT comprises the Scriptures given before the birth of Jesus Christ, commonly designated as the Law and the Prophets, or more verbosely as the Law of Moses, the Psalms and the Prophets. All of these 39 "books" are accepted as canonical in Judaism as well as in Christianity. The OT was mostly written in the Hebrew language, though parts of the prophet Daniel were written in the Aramaic language.
The NT comprises the four Gospels [Matthew, Mark, Luke, John], the book of Acts, the letters of [the apostle] Paul, and the General Epistles, plus the Apocalypse (aka Revelation). These 27 "books" are accepted as canonical in Protestant Christianity. The NT was written in "Koine" Greek, which was the language spoken throughout the lands once conquered under the empire of Alexander the Great.
For further information, consult any reputable Bible dictionary, or refer to http://en.wikipedia.org/wiki/Bible and the various linked pages.
The word "testament" is also understood as "covenant". This word is found in many places in the English Bible.
The main focus of the Go Bible Forum is for matters relating to the application itself, or to Bible translations as possible candidates for porting to the Go Bible platform.