The coin is flipped three times. What is the probability that it will land heads twice and tails once?

Note that it makes no sense in what order this or that side of the coin will fall out. The main thing is that two heads and one tails should come up in total. However, for the sake of definiteness, we will assume that first two heads come up, and then tails come up.
A coin has only two sides, and the case when a coin stands on an edge is usually excluded in school problems. Then the probability of getting the first head is 0.5, the second head is 0.5 and tails is 0.5.
To determine the overall probability, you need to multiply the resulting probabilities:
0.5 * 0.5 * 0.5 = 0.125.