Learn Polish: Kiedy jestem głodny, jem obiad. - When I am hungry, I eat lunch.

The word głodny is the masculine form of the adjective for "hungry". If a woman is speaking, she would change the ending to match her gender and say Kiedy jestem głodna.

Why isn't there a word for "I" before jestem and jem?

In Polish, the verb endings already tell you who is doing the action. Both jestem (I am) and jem (I eat) are in the "I" form, so you don't need to add the pronoun ja unless you want to add special emphasis.

Since obiad is the thing being eaten, shouldn't its ending change?

Because it is the direct object of the verb jem, it is in the accusative case. However, obiad is a masculine inanimate noun (a non-living thing), and in Polish, the accusative form for these nouns looks exactly the same as their basic dictionary form.

Does obiad mean lunch or dinner?

Obiad is the main, warm meal of the day in Poland, usually eaten in the afternoon (around 2:00 PM to 4:00 PM). Because of its size and timing, it can be translated as either "lunch" or "dinner" in English.

I learned kiedy as a question word. Can it also just connect sentences like this?