Your Apple ID was used to sign in to iCloud via a web browser....
I have several friends an family that have reported receiving this email. Now I have received a similar message that appears to be an authentic from apple message with authentic Apple Links (I'm a software engineer, I know how to check links). It indicates that someone has signed in with my Apple Id from a browser. I haven't done so. Should I be worried? Well.. #1 the email uses my "real" email address which I have almost never used. I set up an ALIAS email address and everywhere I register email I use the Alias. Secondly, I think my password is around 30+ mixed alphanumeric + symbols. Nobody could possibly guess it.... and a Brute Force attack would take an eternity. I run strong antivirus. What's going on? This would be bad. They could lock my devices. Read my email. etc. Spoof email?