You are tossing 3 times. It means there is total 2^3 = 8 possible outcomes and each outcome have the same probability 1/8 = 0.125. You have chosen 1 of the 8 outcomes and thus it has probability 1/8 = 0.125
This means the probability for your combination of h,h,t is just as likely as h,h,h or t,t,t or in any other of the 8 combinations. It seems a bit counter intuitive to humans, because they think (h,h,t) is more likely than (h,h,h) and that intuition is also correct, if the order does not matter.
2h and 1t in any order have 3 outcomes, which you can calculate as:
3!/(2h! *1t!)= 6/2= 3 possible combinations/outcomes. This probability is 3 out of 8 possible outcomes or 3/8= 0.375. But if you pin point a unique outcome (h,h,t) from those 3, it will have the probability 3/8 / 3 = 1/8