Security concerns

If you have 2 Factor Authentication enabled on your account, someone may be trying to sign into your account. Unless they can access one of your trusted devices to receive a code, they won't be able to sign in. You should be okay without doing anything.

See this document so you'll know what to do if you ever believe your Apple ID has been compromised: If you think your Apple ID has been compromised https://support.apple.com/en-us/HT204145

Also think about Increasing the Security of your Apple ID https://support.apple.com/en-us/HT201303

Someone is probably trying to sign in, which generates the text with the verification code. They can't sign in because they can't get a code. It goes to your phone because it is a trusted device.

You are very welcome.