People use traps to capture an animal or a person. We also use the word "trap" when a person feels helpless and cannot change a situation.
Look at the picture above. Someone is trying to trap this mouse. There’s a piece of cheese in the trap. If the mouse takes the cheese, the trap will snap shut on top of him and he will be trapped (or he will be killed).
In these sentences, the word "trap" is a verb:
I trapped a fly in my hands before letting him go.
Some kids in the park trapped a frog.
Andrea is trying to trap her boyfriend into getting married.
Workers at the factory were trapped inside the building when a fire broke out. Many of them died.
In these sentences, the word "trap" is a noun:
The government set up a trap to catch some drug dealers.
This dark alley looks like a trap. Let’s get out of here.
I set a trap to catch the rabbits that are eating from my vegetable garden.
I trapped him.
The word "trapped" is also an adjective:
Sam feels trapped in his job.
Rhonda feels trapped in her car all day because she travels a lot.