This is the 4825th most frequent Russian word.
извиниться
To apologize.
The verb 'извиниться' is used here in the infinitive form to express the need to perform the act of apologizing.
Мне нужно извиниться за произошедшее.
I need to apologize for what happened.
The verb 'извиняться' is conjugated in the present tense to describe an ongoing action of apologizing being performed by a third person.
Он извиняется за свои слова.
He is apologizing for his words.
The verb 'извиниться' is conjugated in the future tense to denote the planned act of apologizing.