What does this email mean, "Your 2024 tax return was accessed?"

This is a safeguard that is built into TurboTax. 

If you "ACCESS" your tax return from a location that TurboTax doesn't know you will get a message or Email stating that this happened and that you should contact us if it wasn't you.

It is a notification that a different device from the last time was used to access your account.  If you are concerned that someone other than you accessed your TurboTax account.  Use this link to contact customer support.  

That notice is also sent if you simply downloaded a copy of your Online tax file recently.