I would say that business communication skills are the abilities to express yourself clearly and concisely in a variety of ways. In other words, you need to be able to get your point across to people quickly and you need to be able to do it verbally (face to face), on the telephone, or via email. You need to be able to change your tone and vocabulary and such depending on the situation -- for example, whether you are trying to impart information as opposed to trying to persuade people.
These things can improve your personality by making you better at understanding and communicating with people. This will allow you to get along with people better because you will be better able to get your feelings and ideas across to them.
Business communication skill, or for that matter any interpersonal communication skill, refer to the ability to make others understand whatever message or information you want to convey to them. Equally important in communication skill is the ability to understand what others are trying to convey to you. As a matter of fact, understanding others is a very important requirement for making oneself understood. This constitutes the basic communication skill. In addition, advance communication skill, also involves convincing others about specific issues of importance to you.
Communication skill is a very useful skill for success and happiness in personal life as well as in work. Good communication skill helps individuals to develop better relationships with others and to obtain their cooperation and support. However, in management profession communication skill have added importance, because management work involves substantial amount of working with other people. It helps managers to get better output from their subordinates, by motivating them better, making them understand their task better and developing good interpersonal relationship with them It also helps to obtain cooperation from colleagues and seniors.