Learn Romanian: Ursul mare doarme iarna. - The big bear sleeps in the winter.

In Romanian, the word for "the" is attached to the end of the noun instead of being a separate word. The base word for bear is urs. Because it is a masculine word, we add -ul to the end to make ursul (the bear).

Why is the order ursul mare instead of mare ursul?

Adjectives (describing words) almost always come after the noun they describe in Romanian. So instead of saying "the big bear", the sentence literally says "the bear big" (ursul mare).

The dictionary says "to sleep" is a dormi. Why is it spelled doarme here?

Romanian verbs often have small vowel changes in the middle of the word when they match the subject. For a dormi, the letter o changes to oa when we say he, she, or it sleeps (doarme).

The translation says "in the winter", but where is the Romanian word for "in"?

You do not actually need a word for "in" here! In Romanian, you can talk about something happening during a season by simply using its definite form. Iarnă is winter, and iarna literally means "the winter", but in this context it acts as a time word meaning "in winter" or "during the winter".