This is the 561st most frequent Portuguese word.
tornar
"To become," "to return," or "to make" (context-dependent).
In this sentence, 'tornar-se' means 'to become.' It is a reflexive verb form used to indicate a change of state or profession.
Ele quer tornar-se médico.
He wants to become a doctor.
Here, 'tornar' is used transitively to mean 'to make.' It expresses the causation of a condition or possibility.
O esforço tornou isso possível.
The effort made it possible.
In this case, 'tornar-se' implies a potential transformation from one state into another.