Go to the “Backup” sidebar: you will see 12 words one by one there. Write down a copy of this sequence of words carefully. After it, you will be required to retype all 12 words in the right order to confirm your backup. Store your copy of these 12 words (a mnemonic phrase) in a very safe and secure place and never give it to anyone you don’t want to have access to your funds.
Never switch off your wallet without saving your 12-word backup phrase: it’s the only way to access your funds.