When you bail someone out of jail, you become responsible for ensuring that they appear at all required court hearings and comply with any other conditions of their release, such as checking in with a probation officer or staying within a certain geographic area.
Specifically, when you post bail on behalf of someone else, you are assuming the role of a surety, which means that you are essentially guaranteeing to the court that the defendant will appear at all required court hearings. If the defendant fails to appear in court or otherwise violates the terms of their release, you may be held liable for any fines, penalties, or other consequences associated with their failure to comply.
Posting bail on behalf of someone else is a serious commitment, and should not be taken lightly. Before agreeing to post bail, it is important to carefully consider the risks and benefits involved and to make sure that you fully understand your legal obligations.