The size in the product name is in centimeters, not a clothing size.
A three-part size, such as 24.0x13.0x4.5cm or 20*10*10cm, is the bag's three outer measurements. A two-part size is the two measurements given for that bag. A single number, such as 35cm, is the one measurement listed.
The asterisk and the letter x mean the same thing. They separate the measurements.
To compare in inches, multiply centimeters by 0.39. A 30cm side is about 12 inches. The centimeter figures in the product name are the listed size.