This is the 13th most frequent Spanish word.
en
"In" or "on."
Here, 'en' is used to express location or place.
Vivo en España.
I live in Spain.
In this instance, 'en' indicates the position of the object on a surface.
El libro está en la mesa.
The book is on the table.
Here, 'en' is employed to specify the mode of transportation.