What are the need-to-know body language movements and what do they indicate?

As it is one of the most secret languages around the world , all use it but few understand it , so it needs special reading & explaining for the hands , arms shoulders move , & how is eye contacts during body movements and self express , how is the nerve & voice tone.

the body language is communication without words.its anything someone does to which someone assigns meaning , its nonverbal movement and gestures that are communicating interest ,enthusiasm and positive reactions to what someone saying .knowing the body language make people deal with each other very easy .

body language indicate that the other person is relax or upset to deal with you .

Actually yes, because most of the communication is done through non-verbal means rather than verbal ones. So, a manager or a leader should try to understand the body language in order to communicate well, but should not just focus on body language and leave the obvious message that is coming from someone's mouth. 

Body language is a great language that every manager should take into consideration. It clearly shows the condition and the fillings of everyone. As the most important skill of every managerial role is to understand and help others, accomplishing company's targets,one must never underestimate body language.

Usually there are either signs of openness or signs of discomfort in any new situation. Before naming them it is important to not judge someone just because of the way he is sitting or facial expressions as they can be deceiving such as the common crossed arms. Many people assume crossed arms are not a sign of openness and that may be the case, or- it can simply mean the person is cold. Usually though, open and relaxed signs will show and will be felt mutually- mainly the smile and the relaxed body movements. I hope this helped!