The word "culture" is tricky because it can be used as an uncountable or a countable noun. It also has various meanings. A better understanding of this word will help you with the writing task that we've been working on, so let's look at some definitions and uses.
1. Culture (uncountable): don't use with "a", don't make it plural
This means the customs, beliefs, way of life, art, music, literature or social organisation of a group of people.
- I'm studying European culture. (everything from beliefs to art)
- This city is full of culture and history. (art, old buildings, traditional food etc.)
2. Culture (countable): a culture / different cultures
When we make 'culture' countable, we are usually* talking about the group of people itself. So, 'a culture' can be similar to 'a society' or 'a community'.
- Children are taught to respect different cultures. (different groups of people)
- Traditional cultures are disappearing. (traditional societies or communities)
You might also see "a culture" used to describe an "attitude" e.g. The manager is trying to create a culture of success.