Idiom: to run into (someone/something); inseparable phrasal verb.
First Example: Lisa went to her favorite restaurant in her old neighborhood, and she ran into her ex boyfriend. He said "Hi" but she ignored him. She didn't want to see him.
Meaning: "to run into (someone/something)" means to meet by accident or chance; if you "run into" someone, you were not expecting to see them. In this example, Lisa went to the restaurant because she liked the food and did not expect to see her ex boyfriend. This idiom is usually used when you run into another person, but it can also be used with any situation you find by accident or chance (as below). It's an inseparable phrasal verb, which means the object always comes after "into."
Here is another example:
Second Example: Kurt was hiking in the mountains when he ran into a mountain lion and her cubs. She hissed at him, and he was really frightened, but she didn't attack him and he got away.
Meaning: In this case, Kurt was not looking for a wild animal, but he almost got hurt. Notice that it doesn't mean that he literally "ran into" the mountain lion - just that he met her by accident.
This idiom is from LSI's book "Reading Connections," which is used in the Level 3 Reading classes. For more information, please visit http://www.languagesystems.com/