"第三产业部门" can be translated as "the tertiary sector" or "the tertiary industry sector" in English.
In economic terminology, the primary sector refers to agriculture, forestry, fishing, and mining; the secondary sector refers to manufacturing and construction; and the tertiary sector, or service sector, encompasses a wide range of services including retail, finance, healthcare, education, entertainment, and more.
So, when referring to "第三产业部门" in English, "the tertiary sector" is a commonly used and accurate translation.