A lot of different things make up a civilization. Mostly, a civilization can be defined as a group of people working together towards a common goal, which can be something as basic as survival, like humans had to work towards when they were still hunter-gatherers, or something more complicated like living in luxury or creating AI, like humans work toward now. Typically, civilizations, especially modern ones, can be very complex, and typically have hierarchies in social class and among other things. They also have many different cultural aspects that have arisen from the many different perspectives of people within those civilizations, such as different religions, art styles or other beliefs. They also focus on getting food and resources necessary to survive, because (obviously) without food, humans can't survive, and so they cannot create a civilization without the necessary factors for survival.
In summary, most civilizations are a group of people working together to survive, and modern civilizations are groups of people, typically very large, working together towards an advancement in the quality of life within a hierarchy with different beliefs and cultural aspects.
Hope this helps!
