In the simplest of terms, manifestation is the art and skill with which people focus their thoughts, beliefs, and energy on a certain goal and dream, and then wish for it to come true. Manifestation is based on the idea that what you constantly and consistently think about, feel strongly about, and work towards, will soon shape your reality and your life, and thus, people use it for the most basic or even the most important tasks in life.
And remember, manifestation is not a trick where the result appears magically, but a way to align your mindset with your goal in such a way that you become more focused, driven, and clear.