。
She's having dinner right now.
Literal
She [topic-は] now dinner [object-を] eating [right-in-the-middle-of-doing-ているところ] is.
ディナー is the loanword for 'dinner,' typically reserved for fancy or Western-style evening meals — restaurant dinners, hotel meals, formal dining. Everyday family dinner is 夕食 or 晩ご飯, while ディナー adds a touch of occasion. The temporal precision of ~ているところ marks the action as right now, this very moment.