This is the 1303rd most frequent Catalan word.
tornin
"Turnin" is the third-person plural present subjunctive or imperative form of "tornar," meaning "they return" or "return (you all)."
Here, 'tornin' is used as the third-person plural present subjunctive of the verb 'tornar', employed to express a wish or hope.
Espero que tornin aviat.
I hope they return soon.
In this instance, 'tornin' is again a subjunctive form, used after an impersonal expression emphasizing obligation or necessity.
És important que tornin els llibres a la biblioteca.
It's important that they return the books to the library.
Here, 'tornin' comes after a negated belief, making the use of the subjunctive mood appropriate to convey doubt or uncertainty.