My name is Dima Simonov. I'm from Novosibirsk. I'm ten years old. I have a coin collection. There are fifty four coins from twenty two countries in my collection. My favourite coin is from New Zealand.
Другой вариант:
There are fifty four pieces from twenty two countries in my collection.
В этом предложении слово "coins" ("монеты") заменено на слово "pieces" ("монеты, части [коллекции]") для разнообразия текста.