A more thorough explanation:

Post can have different meanings in a legal context:

For example, employers must post a notice explaining the Fair Labor Standards Act's provisions and procedures for filing complaints of violations of the Act in conspicuous places where employees are employed.

When you post a letter, you send it by mail.

When you pay a credit card bill, the payment is recorded on a specific date and shown on your next statement.

Posting bail means making a payment to secure the release of someone who has been arrested.

Post hoc means "after this, therefore because of this," and post mortem means "after death."

These examples illustrate how the term "post" can have different meanings depending on the context. It can refer to placing a notice, mailing a letter, recording a payment, making a bail payment, or indicating a time after an event.