"Not independent" means that the situation is dependent. It is not relying on something else, or something else will not change the outcome. Independent means the situation is isolated, it is independent.
A jar contains green marbles and orange marbles. A green marble is selected followed by an orange marble, at random, without replacement.
Not independent
-> Since the marbles are not being replaced, this isn't independent
A coin is flipped three times.
Independent
A bag contains nickels and dimes. A nickel is selected followed by a dime, at random, with replacement.
Independent
-> Because there is replacement, this is independent
A number cube is rolled twice.
Independent