It is generally considered that a person speaks a language fluently if they are able to express themselves clearly and accurately in that language, without hesitation or difficulty. This typically includes the abipty to understand and use a wide range of vocabulary, grammatical structures, and idioms, as well as being able to effectively convey meaning and convey ideas through spoken or written communication. Additionally, a fluent speaker of a language should be able to understand spoken language at a natural pace, without needing frequent clarification or repetition.
There is no strict definition or threshold for what constitutes fluency in a language, as it can vary depending on the individual and the context in which the language is being used. Some people may consider themselves fluent in a language if they are able to hold a basic conversation, while others may not feel fluent until they are able to express themselves with the same level of proficiency as a native speaker. Ultimately, fluency is a subjective concept and can depend on a person's goals and expectations for their language skills.