Sling Money allows you to transfer supported stablecoins to and from external (non-Sling) wallets on the Solana blockchain. This capability is primarily designed to allow people in countries where Sling Money doesn't have fiat payments to participate in the Sling ecosystem.
Step by step
In order to add Stablecoin currency (USDP & USDC) with an external wallet:
Tap your avatar located on the top left your transaction history (should be your initials or any photo you might have taken)
Once the transfer is complete, open your Sling Money App to accept the transfer into your primary Sling Wallet.