Q: I don't live in the United States. Why do I have to learn how to count U.S. money? Why do I have to learn about inches and feet?
A for U.S. currency:
Most if not all coin systems today are based on a unit which can be further divided into 100 parts. In the U.S. one dollar is worth a hundred cents.
The Euro, Peso, Pound, Yuan, Rupee, Lira, Shekel, Kuna/Kroner etc. can all be divided into 100 "somethings". Only the names and values are different from dollars and cents. This is generally useful knowledge: different currencies have much in common.
Most likely thinking about the dollar as your own currency should work in nearly all the early exercises. The only exercises which are likely to cause problems for non-US students are those which require coin recognition. KA students doing the early exercises with money may need to opt out on this subject. On the other hand, being able to look at foreign coins and recognizing their value is a generally useful skill...
For non-native students: U. S. money is based on the dollar which can be subdivided in 100 cents.
1 cent = 1/100 dollar, $ 1 = 100 cents
In addition there are other coins that are often referred to by name instead of value.
1 nickel = 5 cents = 1/20 dollar
1 dime = 10 cents = 1/10 dollar
1 quarter = 25 cents 1/4 dollar
1 half dollar or 50-cent piece = 50 cents = 1/2 dollar
Only a few exercises will ask you to convert from, say, dimes to dollars. Most likely your country too has issued coins of more or less the same fractions of your monetary unit.
Nearly all exercises deal with dollars and fractions of dollars, or sometimes cents.
A for non-metric measurements:
In most parts of the world the metric system has replaced older measurements.
Even so even you are likely to come across some of those units. They may be inches, feet, ells, furlongs, miles - or whatever the older units were in your country.
For that reason most (all?) national curricula have kept older units and length unit conversion as part of maths. U.S. students simply encounter inches and feet and miles and U.S. coins sooner than most.
On the other hand, if you can count biscuits in a pack you can count inches in a foot. In fact, working with feet and inches is less complicated than working with hours and seconds.
Learning about U. S. measurements may help with understanding your own measurement systems.
1 inch = 1/12 foot, 1 foot = 12 inches
1 foot = 1/5280 miles, or 1 mile is 5280 feet
If you are unfamiliar with U.S. measurements you may want to have a look at the 4th grade Measurement and data section, Unit conversion.
If you still feel working with U.S. measurements is beyond you as a non-U.S. student, it is always possible to opt out of exercises until you feel you are ready.