。
She started running the machine.
Literal
She [topic-は] that machine [object-を] began-to-move.
動かす is the transitive counterpart of 動く ('to move'); the trans/intrans pairing pattern (止まる/止める, 開く/開ける, 動く/動かす) is one of the deep grammatical asymmetries between Japanese and English, where the same English verb often covers both. Here 動かす isn't really 'physically push it' but 'cause it to operate' — the verb is also the everyday word for getting machinery, software, or systems running. ~始める stitches onto the masu-stem of any verb to mark the onset: 動かし + 始めた = 'began to operate it'.