sell the house; selling the house (て-form)家を売って combines 家 (house) を (object marker) and 売って, the て-form of 売る (to sell). The て-form connects to what follows; the owner and subject depend on context.
JA: 家の価値が上がったおかげで、彼は家を売って大きな利益を得た。
EN: Thanks to the increase in his house’s value, he sold it and made a large profit.