A lot of minds flicker to answer this and similar questions like “What is the need of a concept ?” or “How to relate a concept to a building form “
Concept is basically an abstract idea of a thought process which leads you to the final outcome. It can be an inspiration like waves of a sea or flower petals.
Concept is the starting point of the design process through which one makes a connection with the people and surroundings. It makes a building more relatable to the masses.
Concept can be a form or its functionality. One can also have a range of concepts stringed together which complement the main bigger concept .
For Example – the concept of Burj Khalifa is based on “organic inspiration” taken from “Hymenocallis” flower (regional desert flower).
Like petals from a stem , the towers wings extend from its central core . Viewed from base or air Burj is evocative of onion domes of Islamic architecture.
Also one can note that the base of the inspiration of Adrain Smith (Chief Architect) was taken from the surroundings of that place focusing on the point that buildings should relate to the place where it is build , hence concepts are important to start with the thought process.