This is the 4257th most frequent Spanish word.
nieto
Grandson.
It refers to a family relationship, specifically the grandson of the speaker.
Mi nieto juega en el parque todos los días.
My grandson plays in the park every day.
It is metaphorically used here to describe a sequence of generations, referring to the offspring of a plant derived from another plant.
Esa planta es el nieto de aquel gran árbol que plantamos hace años.
That plant is the grandchild of that big tree we planted years ago.
It describes a historical context, referring to a generational relationship with a specific person of importance in the past.