To find your account's address, just hover over the label for the selected account — in this case, Account 1 — which will let you copy the account's address to the clipboard. If you're on MetaMask Mobile, you may have to tap a few times.
Click on the three vertical dots on the right-hand side and select the Account details menu (see below):
You will then see:
- QR code for your account
- Your public address
- An option to view your account on etherscan.io
- Export your private key