Doesn't is the common spoken contraction of "does not." It is frequently used in everyday English to express negation in the third person singular form.
Example:
"He doesn't like coffee."
(Instead of "He does not like coffee.")
This explanation is based on the Collins COBUILD Advanced Learner's Dictionary, published by HarperCollins Publishers.
The term "doesn't" simplifies negative statements in English, making communication more fluent and conversational.