。
The company is run as a Japan-China joint venture.
Literal
Company [subject-が] Japan-China joint-venture [by-で] managing.
日中合弁 ('Japan-China joint venture') uses the abbreviation pattern country1+country2+合弁: 日 for Japan, 中 for China. The sentence has a slight agent awkwardness — 会社が...経営しています implies the company manages itself, where the passive 経営されています would be more natural. This kind of agent-structure ambiguity occasionally appears in real Japanese.