This is the 14342nd most frequent Russian word.
отключить
"To disconnect" or "to disable."
In this sentence, "отключить" is used in the context of turning off electrical devices or systems, specifically the light.
Я забыл отключить в комнате свет перед уходом.
I forgot to turn off the light in the room before leaving.
Here, "отключить" refers to disabling or blocking access or functionality of a system, such as server access.
Администратор смог отключить доступ к серверу для безопасности.
The administrator was able to disable access to the server for security.
In this usage, "отключить" pertains to turning off or muting notifications, usually on electronic devices.