Acceleration due to gravity is defined as the acceleration produced in a falling body due to the force of gravity. It is denoted by “g” and its value is 9.8m/(sec*sec).
The value of “g” does not depend on the mass of the falling body, it means if two objects say a cotton ball of mass 100 gram and an iron ball of mass 100 gram are allowed to fall in a vacuum tube (free from air resistance) from some height, then both the objects will hit the ground at the same time because both get accelerated towards the ground with the same acceleration i.e 9.8 m/ (sec*sec).
In simple words, 9.8 m/(sec*sec) means the velocity of a falling body increases by 9.8 m/sec after every I sec.
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