The Cash Wallet holds the SWT you have available that's ready to use within the Swarm City marketplaces.
Users can receive SWT Cash by either exchanging shortcodes with another user, completing offers in Swarm City marketplaces, or by transferring SWT from their Reserve Wallet.
SWT sent to the public address on your wallet will not be received into the SWT Cash wallet, but instead it will be received and stored in your SWT Reserve Wallet until you are ready to use in a marketplace.
In order to use SWT from your SWT Reserves you must first transfer it to your Cash Wallet.
IMPORTANT NOTE: You will need a small amount of eth for gas in your wallet to move the SWT into your Swarm City Wallet and to transfer it from your Reserve Wallet into your Cash Wallet. Once funds are received into your Cash Wallet to use within the marketplaces or send via shortcode, you will no longer need eth for each transaction. Reserves can not be sent via shortcode to other users without first being transferred to your Cash Wallet.