。
She took two pieces of luggage with her.
Literal
She [topic-は] luggage [object-を] two-pieces carried went.
２個 (にこ) uses the counter 個 for general objects. 持っていった uses ~ていく for motion away from the speaker. The specific count ２個 shows how counters slot naturally into Japanese sentences — they occupy the same position a vague quantity like たくさん would, without requiring any structural change.