Thivim Train Station Is directly inland from the main resorts of Calangute and Baga and is the main station for anyone staying at any of the northern tourist areas in Goa. There is also Margao (Madgoan) and Vasco train stations which you might arrive at depending which line you are travelling on. Trains from Delhi might only stop at Margao or Vasco, although trains from Mumbai pass through Thivim on the way to Margao.
Thivim is just 16 minutes from the market town of Mapusa, and 30-40 minutes from the beach resorts.
More information on taxi prices and a map of the station can be found on here