A spokesman is a man whose job, at least for that day, is to speak for a group — a company, a government office, the police, a football club — so that what he says counts as what the group says. The key idea is that he is not giving his own opinion. He is a mouth for other people. When you read "A spokesman said the company was sorry," the company is sorry; the man is just the one who opened his mouth. Sometimes it is a permanent job with an office and a title. Sometimes a group just picks one person to go out and talk to the reporters that afternoon, and for that afternoon he is the spokesman. Note the -man ending: for a woman you say spokeswoman, and many people now avoid choosing at all and write spokesperson, or say "a spokesperson for the ministry." News writing today leans that way, especially when the writer does not know who spoke. Spokesman is still very common and not rude, but it is the older habit. A small extra: people also use it loosely for someone who becomes the voice of a group without being appointed — "he became a spokesman for young farmers" — meaning people listened to him as if he spoke for them all.