。
She helped me pack my luggage into the suitcase.
Literal
She [topic-は] I [subject-が] luggage [object-を] suitcase [into-に] pack [nominalizer-の] [object-を] helped for-me.
Two structural moves work together. (1) The pattern Vのを手伝う ('help [someone] do V') uses のを to nominalize the embedded action and feed it to 手伝う. (2) Inside the embedded clause, the subject 私 takes が, and the embedded clause itself has its own object 荷物 marked with を. So we get nested structures: outer を marks のを (the action), inner を marks 荷物 (the thing packed). 詰める ('to pack tightly, to stuff') is the standard verb for packing a suitcase. With ~てくれる, the helping is a kind act for the speaker.