A more thorough explanation:

Definition: To provide a valid reason or explanation for something, to explain the cause of something, to give a report of funds held in trust, or to take responsibility for one's actions.

1. To explain the cause of something:

Can you account for why you were late to the meeting?

In order to account for the increase in sales, we conducted a market research study.

2. To give a report of funds held in trust:

The accountant will account for all the money in the company's bank account.

The treasurer must account for all the donations received by the charity.

3. To take responsibility for one's actions:

The employee had to account for the mistake he made on the project.

The politician was asked to account for his controversial statements during the debate.

These examples illustrate how the term "account for" can be used in different contexts. In the first example, it is used to explain the reason for being late or to justify an increase in sales. In the second example, it is used to report the funds held in trust by an accountant or treasurer. In the third example, it is used to take responsibility for one's actions, such as a mistake made on a project or controversial statements made during a debate.