This is the 134th most frequent Catalan word.
tornar
"To return" or "to come/go back."
Here, 'tornar' means 'to return' and is used to describe someone going back to a place.
Torno a casa després de la feina.
I return home after work.
In this context, 'tornar' conveys the sense of 'to become again' or 'to be again in a certain state'.
Un dia tornarà a ser feliç.
One day, he/she will be happy again.
Here, 'tornar' is used to mean 'to give back' or 'to return an object to someone or some place.