Your coins are not on the device itself, they are tracked on the Blockchain. Your Ledger device holds and protects the private data useful to access and manage them. These data (private keys) are the certificate of ownership of your coins: they give full access to these coins.
When you want to receive coins, you just have to provide your address to the payer. Your Ledger device doesn't need to be connected as the transaction is made on the blockchain, not on the device itself. Next time you connect your wallet, it will synchronize to the blokchain to display all your past operations and your balance.