To understand this Bible you need to understand Messianic Jews, not an easy thing in itself. A Messianic Jew is a Jewish believer which actually follows the OT mostly (nobody can follow it exactly as a Jew because the temple sacrifices are impossible to comply with since the temple was destroyed). But they are kind of people who have one foot in Old Testament Judaism and one foot in the New Testament.
The translator states that “By clarifying the Jewish nature of both testaments this study Bible seeks to help both Jews and Christians understand better their common heritage.” from biblebuyingguide.com