Greetings, Nadiah217.
I see that you have a few emails stuck in the Outbox in the Mail application on your iPad Air. This is blocking your ability to send an email, and I'm happy to help.
How to force an app to close on your iPhone, iPad, or iPod touch -- First, force close Mail application if it's open, then -- Restart your iPhone, iPad, or iPod touch -- Restart your iPad. Once it's returned to the Home screen, test the issue.
Use Airplane Mode on your iPhone, iPad, iPod touch, and Apple Watch -- If the emails are still located in the Outbox, turn on Airplane Mode. This should allow you to delete the emails. Open the Mail application, and see if you're able to delete the emails in the Outbox. If successful, turn off Airplane Mode and see if you're able to send an email to yourself.
If you can’t send or receive emails on your iPhone, iPad, or iPod touch -- If they're still stuck in the Outbox, remove the account and set it up again.
- On your computer, sign in to your email provider’s website. Make sure that all of your email is there or make sure that your email is saved somewhere other than your iOS device.
- On your iOS device, go to Settings > Accounts & Passwords.
- Tap the email account that you want to remove.
- Tap Delete Account.
- Add your account again.
Let me know how that goes, and take care!