This is the 1451st most frequent Spanish word.
marcar
"Marcar" means "to mark, to dial, or to score."
Here, 'marcar' means 'to indicate or mark' something, like making a choice on a form.
Debes marcar tu respuesta en el formulario.
You must mark your answer on the form.
In this context, 'marcar' is used to mean 'to dial' a phone number.
Voy a marcar el número de teléfono en el celular.
I am going to dial the phone number on the cellphone.
This usage of 'marcar' implies 'to signify or establish' an important change or moment.