Hayaa' itself is derived from the word Hayaat which means life. This term covers a wide number of concepts. In English it may be translated as: modesty, shyness, self-respect, bashfulness, shame, honour, humility, etc. The original meaning of Hayaa' according to a believer's nature, refers to a bad and uneasy feeling accompanied by embarrassment, caused by one's fear of being exposed or censured for some unworthy or indecent conduct which is displeasing to Allaah [s].
Islamically Hayaa' is an attribute which pushes the believer to avoid anything distasteful or abominable. It keeps him/her from being neglectful in giving everyone what is due upon them, and if for any reason he/she is not able to keep up with a commitment then they will feel extremely uncomfortable and ashamed about this. The reason being that Allaah will be displeased by this. Hayaa' plays a huge role in the lives of Muslims because it is a very important part of our Imaan (faith/belief). If we do not have any form of Hayaa' within us then it is most likely that our Imaan is very weak. The Prophet [p] said:
"Faith (belief) consists of more than sixty branches (i.e. parts). And Hayaa' is a part of faith." (Al-Bukhari)