You are being phished. As previous replies have said - DON'T click on the link at the bottom of the email. I've attached two emails below that I have received in recent months - one genuine and one a scam. Look at the difference between them and what happens when you hover your cursor over the hyperlink:
Good email
This one is specifically addressed to me by name and gives my Apple ID account. When I hover the mouse over the hyperlink, the associated URL is almost identical - with the addition of the /uk to reflect my location. The bad one looks like this:
The red arrow show that the email wasn't sent to me by name and it doesn't refer to the account associated with the Apple ID in the body of the email. That's the first warning that this is a phishing attempt. Hovering the cursor over the hyperlink shows that you are being diverted from https://appleid.apple.com to an attack site. There is one golden rule - NEVER click on ANY hyperlink from anyone - and that includes Apple - that takes you to a site to change one of your passwords.