She has been to Paris.

Literal

She [topic-は] Paris [to-に] went [past experience-たことがある].

~たことがある is the standard 'have done X (at some point in life)' construction. Notice the difference from 行っている — that says she went and is still in Paris; 行ったことがある just says she has the experience of having gone, regardless of whether she's there now. This split between resulting-state and past-experience constructions is one of the more useful three-way distinctions Japanese makes around verbs of motion.