Just for understand : Serializable means that the data can be stored. And ,as @maruru said, the data can be converted to a string, then deserializable without losing information. You can define your own serializable Object by defining the toString() method. In my case, i use static method parse and stringify (like JSON)
class A{
...
toString(): string
static parse(serialized:string): A // deserialize - convert to instance
static stringify(instance:A): string // serialize - convert to string
}
In the meanwhile, serialize mean exactly : convert into a format that can be stored ( in a redux store by example) ( not always string, buffer is good too, or binary or anything that can be stored ;) )