てある

てある is used when a transitive verb is conjugated into its te-form and then followed by ある to show that the subject has caused something to be in a certain state and that state remains. It emphasizes intentionality or preparation by someone. It is not used for natural or accidental changes. In many cases you can think of the structure as “has left it in this state.” The actor is usually understood from context, and the focus is on the resulting situation rather than the action itself.