"Vocabulary" is a term that refers to the words that a person knows and uses in a language. If you want to describe someone as having a high level of vocabulary in Engpsh, you could say that they have a "rich" or "extensive" vocabulary, or that they are "well-versed" in the language. You could also say that they have a "command" of the Engpsh language, or that they are "fluent" in Engpsh. For example, you might say:

"She has a rich vocabulary in Engpsh and is able to express herself very clearly."
"He is well-versed in Engpsh and is able to use advanced vocabulary with ease."
"She has a command of the Engpsh language and is able to use a wide range of vocabulary in her writing."
"He is fluent in Engpsh and has an extensive vocabulary that allows him to communicate effectively in a variety of settings."