。
She's making coffee in the kitchen right now.
Literal
She [topic-は] now kitchen [at-で] coffee [object-を] is-brewing.
コーヒーをいれる is the standard collocation for 'making coffee' — the verb いれる (often written 淹れる or 入れる) means 'to brew, to prepare a drink by putting hot water through.' The same verb covers tea (お茶をいれる) — anything pour-and-steep. 台所 ('kitchen') is the native word, slightly homely; キッチン is the loanword used for modern, designed kitchens, especially in real-estate listings. The location of action is marked by で, not に — に would imply existence or arrival, while で marks the venue of an activity.