Reference: Why is knowing your personality important?
(I am talking about Jungian personality types here)
Your personality type can be described as a way of life. It's formed in the very early stages of life and is mostly the result of your genes. It details how you prefer to perceive information and make decisions.
There are a couple of reasons for how you can benefit from knowing your personality type.
1. Uncover your life purpose. The cognitive attitudes will tell you what to focus on life. The hero will show you your biggest strengths. The inferior, your biggest insecurity which you can aspire to to gain happiness. The nemesis your biggest worry, which you can turn into your ally. The critic as the gate to maturity. And the demon as the source of your sin and debauchery, which you should avoid at all costs.
2. Discover your strengths & weaknesses. Your cognitive functions – the elements your personality consists of, will show you what you're naturally good at, and where you suck. For example, having Ni in your cognitive make up, will tell you that you're naturally really good at planning and strategizing, however you'll lack good memory. This will allow you to form relationships with people that complement you.
3. Have better relationships. Knowing other people's personality traits will help you to respond better to their natural needs. For example, knowing that a person is an introvert, you'll want to give him space where they can rest and recharge.
4. Build successful teams You'll know how to motivate other people, for example a Ni Te person will be motivated by autonomy and result focused tasks. You'll know what to delegate, for example being an Se user, you are going to need a person who will remember stuff for you.
Relevant notes:
PN: Why knowing your personality type is important: knowing personality types helps you better understand yourself which let's you develop faster and understand where other people are coming from, enabling you to have better relationships with them.