This is the 638th most frequent Polish word.
polu
"Polu" is the locative singular form of "pole," meaning "field" in English.
In this sentence, 'polu' is used in the context of a physical location—'field', which is in the locative case after the preposition 'na'.
Na polu rośnie zboże.
Wheat is growing in the field.
Here, 'polu' refers to an abstract scientific concept—'field', again in the locative case used after the preposition 'o'.
Rozmawialiśmy o polu elektromagnetycznym.
We talked about the electromagnetic field.
In this example, 'polu' describes a practical working location—'field', employing the locative case preceded by the preposition 'w'.