| Dog | Cat | Dog |
How many words are written in the table above? An obvious answer is 3. However, you could say there are 2 and you can intuit why this is not a wrong answer.
Here is where the type and token distinction comes in handy. In this case, we have 3 word tokens 2 word types. Token and Types can be used for more than just words. They can be used to describe events or entities.
If you were to look outside your window and saw a dog, a cat, and another dog. You could say that you are seeing three different animal tokens and two animal types. This is what philosophers call Universals and Particulars. In this case, the two dogs are examples of particulars that instantiate one universal of "dogness." And one particular of Catness. You can also say that all three are particulars of the universal "animalness." Philosophers use the term instantiate to mean the representation of an abstract object. In this example, the concept of "dogness" is an abstract one, and it is instantiated by an actual dog that you see outside your window. The easiest way to think of Universals is stuff that can be instantiated by particulars at different places at once. (More on this later)
Universals include properties and relations. Properties can be things like roundness, beauty, courage, redness, whiteness, tallness, dogness. Relation are things like being taller than, being next to, being heavier than. Properties can be instantiated by an individual but relations (as you can see by the word "than") by groups of individuals.
Universals are abstract entities that exist outside space-time, while particulars have spatiotemporal locations. That's just a fancy way of saying, they exist at a certain time, and at a certain place. So while the dogs outside your window exist now (and hopefully for a long time in dog years because they are good boys) and occupy a certain location. In contrast, the universal "dogness" doesn't exist at a certain time or place.
Not all philosophers agree that Universal exist. Without getting too much into the weeds of the debate. At one end of the spectrum, you have what are called nominalists.* Nominalists deny the existence of Universals. They hold that things like "beauty" or "justice" are names only and do not pick out any entity or object. On the other side are the platonists. (keep in mind there are various spaces to occupy in this spectrum but I am keeping it simple by positing the two opposing views). Platonists think that Universals are real and exist independently of particulars. You may have heard of Plato's Theory of Forms.
What I have been talking about on this page is called metaphysics, particularly a branch of metaphysics called ontology. Ontology is the study of what exists and doesn't. Metaphysics is more troubling to define as (with everything in philosophy) the debate rages on. For now, we can define Metaphysics as the study of the fundamental nature of reality.
Next: Realism vs Anti-Realism
*There is another type of nominalist that denies the existence of any abstract objects.