Multiply the number of choices for each coin flip and you get 2*2*2*2*2 = 32.
Flip # 1 : 2 choices (h or t), Flip # 2: 2 choices (h or t), Flip # 3: 2 choices (h or t), Flip # 4: 2 choices (h or t), Flip # 5: 2 choices (h or t)
Multiply the number of choices for each coin flip and you get 2*2*2*2*2 = 32.