What will happen if the value of the american dollar decreases

There could be two scenarios. One is the decrease of Dollar with itself and its impact on its economy and second is the decrease of dollar with respect to other currencies.

So if dollar decreases with respect to itself, it means the value of the currency decreases. When the currency depreciates, people will have to pay more to purchase the same product, which means there will be more money circulation within the economy. Prices of the products or services increases which results in the inflation within the economy.

Secondly if the currency decreases against the other country's currency, it means the other currency is getting strong against your currency. You may face to bear more amounts of money for trading with other countries. Imports will be more expensive.

If the money decreases things will be more harder and more expensive to buy

Explanation:

Pretend you have $10 and something you want is $10 it is easier to buy it when the value of money is higher and if the money is lower than it'll be harder to get $10 to buy the item you want