、。
She tilted her head slightly and stood there silently.
Literal
She [topic-は] slightly head [object-を] [tilted-かしげて], silently [was-standing-立っていた].
首をかしげる ('tilt one's head') is a fixed gesture of puzzlement, doubt, or thoughtful consideration in Japanese — the same head-tilt readers know from manga and film convention to indicate 'huh?' or 'I don't get it.' 黙然 (mokuzen, 'silent, speechless') is a literary な-adjective; the と after it (黙然と) is the adverbial と that follows certain manner-modifiers, parallel to mimetic + と. The whole sentence has a still, slightly novelistic quality, painting a moment of quiet uncertainty in physical detail — vocabulary and grammar both selected for atmosphere rather than efficiency.