return "[\"" + this.getClass().getSimpleName() + "\", " + c.toJSON() + "]";

general
1

What does this line of code do: return “[”" + this.getClass().getSimpleName() + “”, " + c.toJSON() + “]”;
what does “[” do?
I thought return is used to return simple individual variable not a statement like above.

2

if class is eg Words and c.toJSON() returns “some code”
then your example return this String :
[“Words”, some code]