General:
* The children were playing in the park.
* Several cats were sleeping in the sun.
* Many cars were parked on the street.
* We bought two new books at the bookstore.
* There were three apples left in the basket.
Specific:
* I have five pairs of shoes.
* There are ten planets in our solar system.
* The company hired four new employees.
* We ate three slices of pizza.
* She gave me two pieces of advice.
More abstract:
* He has a lot of ideas.
* The team made several mistakes.
* We had many opportunities.
Key takeaway: Countable plural nouns refer to things that can be counted individually and take a plural form (usually by adding "-s" or "-es").