EQ or Emotional Intelligence is a person's ability to recognize and understand his own emotions, aswell as the emotions of others. This also includes how the person controls and expresses their own emotions.
As the name implies, Emotional Intelligence or EQ, refers to how a person views and interacts with their emotions and the emotions of others. On the other hand, IQ is referencing one's intellectual or cognitive ability which has more to do with their logical reasoning, ability to apply knowledge, problem solving, memory etc. These sort of Things. Generally speaking, one can't alter their IQ while their EQ can very much be trained and developed.
EQ is important because as human beings, we can't ignore our emotions and how much they influence our day to day lives. Emotions are present in almost everything we do so it is important to be aware of them. As well as be competent in controlling and expressing them. This will have a direct impact in how well we are able to work, learn, train, have good relationships, interact with others etc. Pretty much in all aspects of life.