I have common sense to help me unravel what is going on around me. But each person's common sense is not the same, each of us may look at our social environment differently. What science does is to give us a set of tools that work consistently, no matter who uses them or when they are used. This consistency is reassuring when we have questions to be answered. We want to have good answers, not just answers that are somebody's personal opinion.
Science allows our knowledge of people to grow.
The language used in sociology is like a new language. Some of the words are words we already use, but the meanings have a more precise scientific application. These words are based on the application of theory and research to problems of understanding society and how people interact with each other. So, the vocabulary of sociology has developed a precise meaning. Even thought the words may be familiar, don't take it for granted that you know what they mean.