1.
If someone breaks into a building, they get into it by force.
There was no one nearby who might see him trying to break into the house...
PHRASAL VERB : V P n
2.
If someone breaks into something they suddenly start doing it. For example if someone breaks into a run they suddenly start running, and if they break into song they suddenly start singing.
The moment she was out of sight she broke into a run...
Then, breaking into a smile, he said, ‘I brought you something.’
PHRASAL VERB : V P n , V P n
3.
If you break into a profession or area of business, especially one that is difficult to succeed in, you manage to have some success in it.
She finally broke into films after an acclaimed stage career.
PHRASAL VERB : V P n