Dispensationalist theology is a way of understanding how God works with people throughout history. Imagine you are playing a game with a friend, and you both agree to play by certain rules. But then, you decide to change the rules halfway through the game. This is a little bit like what dispensationalists believe God does.
According to dispensationalists, God has different rules for different periods of time. They call these periods of time "dispensations." So, for example, the period of time when Adam and Eve were in the Garden of Eden is one dispensation, and the period of time after Jesus' death and resurrection is another dispensation.
Each dispensation has its own set of rules that people have to follow to be righteous in God's eyes. For example, during the time of Adam and Eve, the rule was "don't eat from the tree of knowledge." During the time of Jesus, the rule was "believe in me to be saved."
Dispensationalists also believe that God has a special plan for the nation of Israel. They say that God made a promise to the Jewish people that he will one day restore them to their land and give them a special role in his plan for the world. This is called "dispensational premillennialism."
Overall, dispensationalist theology is an attempt to make sense of how God works with people throughout history. By dividing history into different dispensations with different rules, dispensationalists try to understand how God's plan is unfolding and what humans need to do to be a part of it.