Sabbath mode on a GE oven is a feature that keeps the oven heating for long periods, allowing observant Jews to reheat food on the Sabbath without violating their religious beliefs. It is forbidden to light a fire on the Sabbath, and in modern terms, that includes activating electrical devices.
Observant Jews follow restrictions on certain activities during holy days and the weekly Sabbath. Since turning on an oven can violate these restrictions, Sabbath mode allows the user to turn on the oven before the beginning of the Sabbath and keep it running at a low temperature until the Sabbath ends, when he can interact with it once more. Normal ovens have automatic cut-offs that turn off the heat after a period of a few hours to prevent fire, and Sabbath mode overrides these restrictions.