Breakdown of Jutro nocuję u niego sam.
on
he / it (m)
jutro
tomorrow
sam
alone / himself (emphatic) / pure / nothing but
u
at, at the place of
Questions & Answers about Jutro nocuję u niego sam.
Why is it u niego instead of u jego?
The preposition u (meaning 'at the place of') requires the Genitive case. The normal Genitive word for 'him' is jego. However, in Polish, when a third-person pronoun follows a preposition, it gets an extra 'n-' added to the beginning to make it easier to pronounce. So, u jego becomes u niego.
The word nocuję looks like the noun for night. Is it a verb here?
Yes! It is the 'I' form of the verb nocować, which means 'to spend the night' or 'to sleep over'. Because it ends in -ować, it conjugates with -uj- in the present tense, just like how pracować (to work) becomes pracuję (I work).
Does the word sam change if the speaker is female?
Exactly. sam means 'alone' or 'by myself' and is in the masculine form here. Because Polish sentences often drop the subject pronoun (like ja for 'I'), adjectives like this are helpful clues for the gender of the speaker. A female speaker would say sama.