Power is when one person or group has control over another person or group. This could be done using social or political means.
Social power means that one person or group has influence over another person or group by using things like money, fame, influence or popularity. For example, if a group of people is popular at school, they might have social power over other students and be able to bully them or control what they do.
Political power means that one person or group has control over another person or group by using laws, military forces or taking over an area. For example, if a country had strong military power, it could take control of another country or force the people of that country to do what it wants them to do.