。
She came running into my arms.
Literal
She [topic-は] my arm [of-の] inside [into-に] jumped-in came.
Two compound-verb layers stack here. 飛び込む ('to jump in / leap into') pairs 飛ぶ ('to leap') with the inward-direction auxiliary ~込む ('into'); the result is a vivid 'plunge inward.' Then ~てくる adds direction toward the speaker — 'jumped in (and arrived here).' Together, とびこんできた ('came jumping into [my arms]') paints an emotional, physical arrival — typical of a reunion, a child running to a parent, or a romantic embrace. 腕の中 ('inside the arm') is the standard Japanese way to describe being held — the same body-as-container imagery underlies お腹の中 ('inside one's belly,' for unborn children) and 心の中 ('inside one's heart').