It is important to realize that at the same time, the people you talk to are interpreting and judging your behavior. Language is a social behavior. Understanding and interpreting cultural behavior is and important part of interaction. What is appropriate to say and to whom varies considerably from group to group and around the world. If you want to acquire the ability to interact effectively in another language, you have to understand the rules a native speaker uses when speaking.
Differences can lead to misunderstanding.
When people from different backgrounds interact, they tend to judge each other's behavior by their own rules. Directly interpreting values and rules from your own language may cause misunderstanding. Failure in this area can have serious consequences. Grammatical errors are easily excused by native speakers, but these types of errors may lead to judgments of your character. These processes are unconscious.