Staking is a way to lock up your $ROC tokens in return for a high yield, and at the same time support the long-term success of the ecosystem.
When $ROC is staked, you are not able to use it for other purposes, but you will earn a yield. Staking $ROC allows you to support the Blockstars ecosystem and demonstrate your commitment to its long-term success - specifically, your $ROC will be staked to supplement the liquidity of the $ROC:$ROL exchange, which is what allows players to convert their day-to-day rewards into real-world exchange-tradable assets.
More details on staking coming soon.