Meaning: She can speak English easily and correctly.
Choice of Words: Fluently means speaking or writing a language easily and correctly.
Alternative Expressions
She's really good at speaking English.
Meaning: This means that the person is very skilled at speaking English, and can communicate effectively in the language.
Choice of Words: The word "really" is an adverb that means very or extremely. "Good" is an adjective that means having or showing positive qualities. "Speaking" is a verb that means to use your voice to communicate words. "English" is the name of a language.
She can speak English like a native speaker.
Meaning: This means that the person can speak English as well as someone who grew up speaking the language.
Choice of Words: The word "can" is a modal verb that indicates ability. "Speak" is a verb that means to use your voice to communicate words. "English" is the name of a language. "Like" is a preposition that means in a similar way to. "Native speaker" is a noun that refers to someone who speaks a language from birth.