What does "Save item dates before proceeding" mean?

[rayyanmm]

appears when I move an image from one album to another.

Thank you in advance for your time and help!

[deckerst]

This saves the current "file modified date" as a "metadata date", and it is suggested when the file being moved (or modified) does not already have a metadata date.

The reason the app suggests this is because metadata dates are more reliable than file attributes. Aves is a gallery app and not a file manager app, so it cannot control file attributes and the "file modified date" won't be preserved when moving files.