。
She has hoop earrings on.
Literal
She [topic-は] ears [on-に] rings is-attaching.
リング ('ring') here refers to ring-shaped earrings — hoops, in English. Note the contrast with the more conventional イヤリング (Japanese-style 'earring'): リング in this slot evokes a specific style (large, circular). つける ('to attach, to put on') is the workhorse verb for putting on accessories that aren't full clothing — earrings, watches, glasses, badges, makeup, even perfume. The resultative ~ている marks the state of wearing rather than the act of putting on.