A more thorough explanation:

Definition: Confidence refers to a feeling of trust and assurance in oneself or in someone else. It can also refer to a private communication that is meant to be kept secret.

Examples:

• She had confidence in her ability to complete the project on time.
• He placed his confidence in his friend to keep his secret.
• The lawyer could not reveal his client's confidence without their permission.

The first example illustrates confidence as a feeling of trust in oneself. The second example illustrates confidence as a feeling of trust in someone else. The third example illustrates confidence as a private communication that is meant to be kept secret.