Spanish phrase
Lo siento.
Meaning
I'm sorry.
When to use it
It is a brief expression of apology. Used for minor mistakes through serious apologies, common in casual speech though more polite forms are chosen with superiors.
Example dialogue
Lo siento, te empujé sin querer.
I'm sorry, I pushed you by accident.
No pasa nada.
It's okay, don't worry about it.