The animation Asset Details panel is a context-sensitive property editor that allows you to change settings on animation assets, including but not limited to Anim Sequences, Blend Spaces or Anim Montages. The Asset Details panel is visible while in the Animation Editor and consists of settings related to animation assets, however there is an Asset Details panel that is available when working inside the Skeletal Mesh Editor that provides properties that can be changed to affect the related Skeletal Mesh.
Refer to each animation asset's documentation page for a breakdown of the options contained within the Asset Details panel.
Viewing Animation Asset Details
To view the animation Asset Details panel, open your animation asset from the Content Browser:
The Asset Details panel will be located in the left panel of the editor:
You can also Double-click an asset from the Asset Browser panel to open the Asset Details for the asset:
Docked as a tab alongside the Asset Details tab is the Skeleton Tree panel, which shows the skeletal hierarchy of the current Skeleton asset.