"The winter has passed."
Translation:O inverno passou.
In this sentence, 'has' is a helping verb, expressing the past. You don't use the verb 'to have' as a helping verb in Portuguese. English uses a lot of helping verbs to express tense, while Portuguese prefers using inflection (different endings).
EDIT Oh yikes! reading this now I realize how wrong I was. Portuguese does indeed using helping verbs for the compound past. It's amazing how a reading of a grammar book has made everything much clearer.
Often the Portuguese preterite can be translated as simple past in English (passed) or the present perfect (has passed).
The compound past, using ter would express something more like "I have been doing something".
I'm a bit rusty in my Portuguese studies, so those more knowledgeable can correct me.