A terminating decimal is a decimal number that does not go on forever.
e.g. 3/100 = 0.03, 3 7/10 = 3.7, 11/16 = 0.6875
but 100/3 = 33.333333... , 9/11 = 0.81818181...
The last number, 9/11, is a non-terminating decimal and keeps on going on forever. The three little dots at the end of the number is used to show that it is non-terminating.
So, if a decimal number has a fixed number of decimal places, then it is a terminating decimal.