Depending on the text you study, there are a varying number of components of culture as identified by sociologists. In addition, there are subcultures within larger cultures, and there is so much (incredible) variety to explore when examining how and why people interact in societies in the ways that they do. To give you an overview, here are three ideas for you to consider: language, norms, and beliefs or values.
The ability to communicate effectively is crucial to any culture, and language production varies even within a nation of people who are fluent in the same language. Imagine traveling to Finland (assuming you are not Finnish) and trying to communicate without technology, your iPhone, or any other means of translating. As you stand in the middle of Helsinki, you would certainly feel on the outside of their culture—unable to participate.
I remember in my undergrad work, one of my professors asked us to name a variety of objects. One of the examples was a small, flowing body of water that would maybe be found behind one's house. I went to a pretty large and diverse college, and the variety in language was incredible: stream, creek, branch, crick, and brook. Depending on their heritage or where they were born, different Americans have various ways of expressing this one concept. Therefore, knowing the nuances of language in any given culture is crucial. (For the record, I call it a creek.)
How people are expected to act in social situations also varies widely from culture to culture. This is something educators have to adjust to when teaching students from cultures other than the ones they themselves grew up in. Some cultures consider it disrespectful to talk when adults are talking, and other cultures are much more interactive, with an expectation that many people can talk at once—and there is no disrespect intended. In some cultures, young children are accustomed to being taught by older children—not by adults.
From checkout lines at the grocery store, to where you should stand on an escalator (I got this one "wrong" in a big city once), to how one should order at a restaurant, every society is filled with "norms" of expected behavior. Using the escalator example, I am from an incredibly small town with 0 escalators, as far as I know. When I encounter one, people generally get on and "ride" passively to the top. I was shocked when I was chastised in DC for standing in the middle of the escalator to the subway, as people needed to "get by" in their rush to make the train. I had no idea of this cultural norm. Now I know—stand to the right if I don't plan to actually walk on the escalator.
Beliefs and Values
A core component in any culture is what they deem important. This includes religious beliefs and many others, which can be either explicit or implicit. For example, most Americans believe in the idea of the American Dream—that people who work hard will be rewarded for their work. American culture also values youth and beauty, and lots of companies make a fortune marketing these core values to people searching to fulfill these ideals. People value marital monogamy and cultural diversity, though the real life applications don't always match the stated values. As a teacher, I value education, as I've seen how it has changed my life trajectory as well as the trajectory of many of my former students.