Why is it important for a country to have
more exports (sell) than imports (buy)?

It is important for a country to have more exports because if the country imports more than they export money will be leaving the country and this will not be beneficial to the country's economy. The more a country exports the more domestic economy activity is taking place. More exports means that there will be a need for demand which will stimulate the production companies creating jobs and increasing revenue, so in conclusion exports are more important for a country, as it is beneficial to them.