The simplest way to understand “staking” is interest provided to your Pandacoins stored in the PandaBank, like interest would be applied to your bank account. If you are staking, you will earn 2.5% interest on all of the coins which which you are staking. So, if you have 100 coins, you will earn approximately 2.5 Pandacoins every year. This will wind up being slightly more due to compound interest, but you get the idea. Beyond providing interest, it also helps to secure the Pandacoin network, by using a small percentage of your computer’s processing power in order to make transactions. The amount of processing power used is minimal, such that it would be completely unnoticeable, however every little bit helps to make the network strong and secure.

If your PandaBank is closed, or offline, you cannot stake. In order to stake your computer must be on, your PandaBank must be open, and unlocked for interest staking, and it must have some amount of Pandacoins inside. Essentially, in return for the small amount of processing power you’re donating to the Pandacoin network, the network pays you in interest! It is important to remember that it takes 3 days after receiving coins for those coins to begin to stake. If you have Pandacoins, staking is an excellent way to strengthen the Pandacoin network. Do your part, and stake with your Pandacoins today!

More info can be found here: http://dev.digitalpandacoin.org/index.php/2015/05/31/pandabank-2-5-annual-interest-staking-faq/