Learn Hardcore Polish: On pracuje w centrum konferencyjnym.

In Polish, personal pronouns (like On “he”) are usually dropped because the verb ending already shows who’s doing the action. You say Pracuje w centrum konferencyjnym and it still means “He works in a conference centre.” Including On adds emphasis or clarity, for example to contrast with someone else:
– Ona pracuje w biurze.
– On pracuje w centrum konferencyjnym.

What tense and person is pracuje, and how is it formed?

Pracuje is the 3rd person singular present tense form of the verb pracować (to work). To form it:

Remove the infinitive ending -ć from pracować → pracowa-
Adjust the stem to pracuj-
Add the ending -e for “he/she/it”: pracuje.

Why is the location phrase centrum konferencyjnym in this form? Which case is it?

The preposition w (“in/at”) requires the locative case to express location. Here centrum konferencyjnym is locative singular. The noun and its adjective both take the locative endings.

Why doesn’t centrum change its ending for the locative case?

Centrum is a foreign-derived neuter noun ending in -um that is indeclinable in the singular. Its form stays centrum in all cases (nominative, locative, etc.).

Why isn’t it we centrum instead of w centrum?

Polish uses we instead of w only before clusters of two or more consonants (e.g. we wtorek, we wszystkim). Centrum starts with the single affricate /ts/ (one sound), so the short form w centrum is correct.

Why does the adjective become konferencyjnym with -ym at the end?

Konferencyjny is the base adjective (“conference-…”) for a neuter noun. In the locative singular (required by w), neuter adjectives take the ending -ym:
konferencyjny → konferencyjnym

Where is the stress in pracuje, centrum, and konferencyjnym?

Polish stress is almost always on the penultimate syllable:
• pracuje: pra-CU-je
• centrum: CEN-trum
• konferencyjnym: kon-fe-REN-cyj-nym (stress on -cyj-)