This is the 13487th most frequent Spanish word.
regalarle
"To give (someone) a gift."
The word 'regalarle' here is used as an infinitive verb meaning 'to gift to him/her', referring to 'a mi padre' in this context.
Quiero regalarle un reloj a mi padre.
I want to gift him a watch to my father.
In this example, 'regalarle' is as an infinitive verb form meaning 'to gift to him/her', referring to 'a la profesora'.
Decidieron regalarle flores a la profesora por su ayuda.
They decided to gift her flowers to the teacher for her help.
Here, 'regalarle' operates as an infinitive reflecting the action of gifting to 'su novia' within the sentence.