$WALLET, $xWALLET and $stkWALLET are three tokens that serve different purposes in the Ambire ecosystem.
$WALLET is the main token, which can be used to pay your gas fees in Ambire Wallet, traded on is used to reward users of Ambire wallet and can also be traded.
xWALLET (token address) represents the share you have in the $WALLET staking pool. When you stake $WALLET you get xWALLET as a representation of your staking position. This means that xWALLET holders will be able to vote in the WalletDAO and the two tokens are interconnected through the staking mechanism.