Learn Russian: Волейбол — мой любимый спорт.

In Russian, the present tense of the verb "to be" (is, am, are) is normally skipped. When you connect two nouns to say one thing is another, like волейбол (volleyball) and спорт (sport), you write a dash (—) between them to take the place of "is".

Why do we use мой here instead of моя or моё?

The word мой (my) must match the gender of the noun it belongs to. Here, it describes спорт (sport). Since спорт ends in a consonant, it is a masculine noun, so we use the masculine form мой.

Does любимый also change its ending based on the noun?

Yes! Just like мой, the adjective любимый (favorite) uses its masculine ending (-ый) to perfectly match the masculine noun спорт. If you were describing a feminine word like игра (game), it would become любимая.

Could I swap the two halves and say "Мой любимый спорт — волейбол"?

Yes, you absolutely can. Russian word order is very flexible. Swapping them means "My favorite sport is volleyball," which is perfectly natural and just shifts the focus slightly, exactly like it does in English.