。
She says she'll call you later.
Literal
She [topic-は] later you [to-に] phone [object-を] does [quotative-と] is-saying.
電話をする ('to make a phone call') is the everyday alternative to 電話をかける ('to place a call,' literally 'to hang the phone'). Both are correct, but 電話をする leans casual and modern, especially when the call is treated as a routine event. 言っています ('is saying') in resulting-state ~ている marks an ongoing report or recurring claim — she's been saying this. The dative-に on 'you' marks the call's recipient.