To be aware of where one’s advantage lies, or to understand what actions will benefit oneself the most.

समझना कि कहां से फायदा मिलेगा

English Usage: He knows which side his bread is buttered on, so he always supports his boss's decisions.

Hindi Usage: उसे पता है कि फायदा कहां से मिलेगा, इसलिए वह हमेशा अपने बॉस के फैसलों का समर्थन करता है।