Most often we use it in the phrase "share the same sentiment." It can be good or bad.
<em>I was very happy about the game, but he did not share the same sentiment.</em>
<em>I looked at her and saw her cry. In that moment, I knew we shared the same sentiment.</em>
<em>He thought it was funny. I did not share the same sentiment.</em>
We also use it a lot to refer to someone's expression towards our situation.
<em>He said he felt bad for me. I appreciated the sentiment.</em>
<em>My mom says she is excited. I know she is not actually excited, but I still appreciate the sentiment.</em>
Here are some more examples of other uses. It is quite "literary" and not very commonly used.
<em>Her poem was amazing. It held a beautiful sentiment.</em>
<em>She said that man is a hero because he is a soldier. It was an interesting sentiment, considering she hates war and violence.</em>
The adjective "sentimental" is also good to know. I think it is a little more common than "sentiment."
<em>The movie made her sentimental.</em>
<em>The ice cream gave me sentimental feelings.</em>
<em>He started crying when the puppy found a new home. I didn't know he was so sentimental.</em>