Uncountable nouns are things that we can't count individually, like:
* Substances: water, air, sand, rice, milk
* Concepts: advice, information, happiness, knowledge, time
* Abstract nouns: beauty, music, anger, love
* Some materials: furniture, equipment, luggage
Instead of trying to make a plural, you can:
* Use a quantifier: "a piece of advice," "two bottles of water," "some information"
* Use a collective noun: "a flock of birds," "a herd of cows"
* Use a different noun: "grains of rice," "pieces of furniture"
Let me know if you have a specific noun in mind and I can help you find the right way to express it!