railway company; railroad corporation
Refers to a company that operates railway services. Common in business and news contexts.
JR East is a major railway company in Japan.
That railway company is constructing a new line.
鉄道 means 'railway' or 'railroad' as a system or infrastructure, while 鉄道会社 specifically refers to the company that operates it.
Compound of 鉄道 (railway) + 会社 (company).