If you and your friend both have verified Mode accounts, sending and receiving Bitcoin is indeed free and instant! Just tap Send on the bottom menu > Choose your friend from your Mode Contacts list > enter the Bitcoin amount > confirm and you're done!
If your friend doesn't have a Mode account yet:

1) Invite them to join Mode by tapping on Send on the bottom menu > Contacts > Invite (Receive £10 worth of BTC each for every new friend you invite. T&Cs apply.)

2) Send BTC from your Mode account to their external Bitcoin wallet. Please note that we charge a blockchain fee to transfer Bitcoin to non-Mode wallets.