Ask your friend to predict the outcome of a ₹ 1 coin you toss. Do you see that your friend could guess heads or tails but could not know for certain? That's randomness! All possible results are known, but each individual try is unpredictable.                                                                                                                                                                              [Page No. 157]

Yes. Before the coin lands, your friend knows the only two possible results heads or tails, so they can name one of them as a guess. But they cannot know which one will actually come up, because a coin toss is a random experiment: the result depends on tiny, uncontrollable details of how the coin is flipped and how it lands.

This is the heart of randomness: knowing all the possible outcomes is not the same as knowing the actual outcome.
Over many tosses your friend's guess would be right about half the time,
because each side has probability $\frac{1}{2}$; but for any single toss the result stays unpredictable.
The list of possibilities is known, yet each individual try cannot be predicted with certainty.