[verb て-form] + いる場合じゃない
The expression ている場合じゃない means "this is no time to be doing ~" or "now is not the situation for ~". It is used to criticize or urge someone (including oneself) who is doing something inappropriate or leisurely when there is something more urgent or important that demands attention.
ばあい場合 means "situation" or "case", and じゃない is the informal negative of だ. The literal meaning is something like "it is not the situation to be doing ~", which conveys that the current action is out of place given the circumstances.The pattern typically carries a tone of urgency, scolding, or self-motivation. It implies that the listener (or the speaker themselves) should stop what they are doing and focus on something more pressing.
In more polite contexts, じゃない can be replaced with じゃありません or ではありません.
It is also common when talking to oneself, as a way to motivate or scold oneself into action.