As a verb, it means:
* To feel curiosity or amazement: "I wonder what's inside that box."
* To consider something thoughtfully: "I wonder if this is the right decision."
Here are some examples:
* I wondered about the meaning of the poem.
* She wondered if he would call her back.
* We wondered at the beauty of the sunset.
However, "wonder" can also be a noun, meaning:
* A feeling of amazement: "The children were filled with wonder at the circus."
* Something that causes amazement or awe: "The Grand Canyon is a natural wonder."
It's important to look at the context of the sentence to determine if "wonder" is being used as a verb or a noun.