These are always the most confusing tabletop rpg dice. As described above percentile dice are the two D10’s. One is a regular the other has a zero after all the numbers. Because of how these work new players often find that these dice the most confusing to read.
The way to read it is to consider the D10 with just one number as the ones column of a number. For example if you’re the role 5 on that die you have a 5 in the ones column. The dice with two digits is the tens column. For example if you were to roll a 20 on that die the number will be 20 not a 2 because the 2 in in the tens column. The trick is that to get the number rolled you add the two dice together. For example add the 20 on the two digit die with the 5 on the single digit die to get 25.
Rolling 100 or rolling 1-9 get a little more complicated. The 00 when added with a 1-9 on the single die gives you the number in the single digits, for example if you roll 00 and a 4 the number you get is 4. This changes however if you roll a 00 and then of 0 on the single digit die. When this is done you get 100.
Remember 000 = 100
One trick I tell players is that if you roll a 00 and a 1-9 on the single digit die move the 00 from sight and only read the single digit die.