、。
She grabbed my arm and held me back as I tried to leave.
Literal
She [topic-は] my arm [object-を] grabbed [and-て], let's-leave [trying to-とする] [nominalizer-の] [object-を] held-back.
Several rich grammar layers. (1) The te-form つかんで chains the grabbing into the holding-back. (2) 帰ろうとする ('be about to leave / try to leave') uses the volitional 帰ろう + とする for an imminent or attempted action. (3) The whole clause 帰ろうとする is then nominalized with の and marked with を as the object of 引き止める ('to detain, restrain, hold back'). The pattern [verb-clause]+のを引き止める is the standard frame for stopping someone from doing something — the の-nominalization turns the would-be action into something graspable.