This is the 4302nd most frequent Spanish word.
por
"Por" is a Spanish preposition meaning "through," "for," "by," "because of," or "on behalf of," depending on context.
In this sentence, 'por' signifies the reason or motive for going to the store, which is to get bread.
Voy a la tienda por pan.
I'm going to the store for bread.
Here, 'por' is used to indicate the length of time during which the action occurred.
Trabajé por ocho horas hoy.
I worked for eight hours today.
In this example, 'por' is used to indicate an exchange or substitution.