There is not a fixed rule for the formation of the uncountable nouns.
Uncountable nouns cannot be used with the indefinite article (a/an) or numbers.
They can have:
- Only the singular form that cannot be made plural (advice, baggage, energy, furniture, homework, information, money…);
- Only the plural form that cannot be made singular (clothes, groceries, news, regards, thanks, the Spanish…).