Urban sprawl can affect people both directly and indirectly.
The most direct effects of sprawl are felt by the people who live in and around the city in question. There are both good and bad impacts. On the good side, some of these people can move out of cities to places where they have more space. They can have backyards in which their children can play. They can have larger homes. On the bad side, the sprawl tends to lead to traffic problems. As cities and suburbs sprawl out horizontally, more and more cars need to get to various places. Typically, this leads to long commutes, which can be stressful as well as time-consuming.
The less direct effects of sprawl are more difficult to feel in the short run. Sprawl can mean that green spaces near the city are destroyed and people lose the feeling that they are close to nature. Sprawl can mean the loss of farming near the city, depriving people of things like fresh, locally-grown foods. In the big picture, sprawl tends to lead to things like more energy use (for the bigger homes and the commutes) that can help to drive global climate change.