。
She's painting a picture.
Literal
She [topic-は] picture [object-を] is-drawing.
描く covers a whole range of visual creation in Japanese — drawing, painting, sketching — and even extends metaphorically to depicting in writing or imagining ('未来を描く'). The kanji literally suggests tracing a hand (扌) along a contour. Here ~ている marks an action genuinely in progress: the brush or pencil is moving on the page right now. This contrasts with verbs of change like 結婚する, where ~ている describes a resulting state instead.