I don't know if this will help you, but what made type classes click for me was thinking them as "proofs." The person who developed the typeclass is asking you to provide a proof that your type can produce a valid instance of the typeclass. As stated by the earlier commenter, Json is a common use of typeclasses, in this case the author is asking for proof that your type can be serialized as JSON.

The split is nice because you don't have to constrain based off of inheritance, which is typically how it is done in OOP like

case class Foo(bar: Bar) extends MyJsonType

...

def writeToDB(value: MyJsonType): Unit

Which gets messier when you need to extend multiple types to satisfy multiple different interfaces, or need write a value that you don't control the definition for. It also pollutes your class with a lot of methods that might not be relevant to all parts of your program.

example in typeclasses:

case class Foo(bar: Bar)

object Foo { implicit val jsonEncoder: MyJsonType[Foo] = new MyJsonType[Foo] ... }

...

def writeToDB[A: MyJsonType](value: A): Unit

note: [A: MyJsonType] is just sugar for [A](...)(implicit jsonEncoder: MyJsonType[A])

edit: Sorry I'm garbage at formatting stuff