、。
She's shy and always at the back.
Literal
She [topic-は] shy is-and, always behind's side [in-に] is.
内気で uses the te-form of the na-adjective 内気 (= 内気だ + て → 内気で), linking it to the next clause. 後ろの方 ('the back area') uses 方 ('direction, side') for vague spatial reference, often paired with の: 後ろの方 ('toward the back'), 前の方 ('toward the front').