Name of the element that pops up when you mouse over a folder in Windows 10?

This is called the "Pop-up Description", and it can be disabled and enabled (see link).

The time it takes for it to pop up is called the "Mouse Hover Time". It is specified in the registry key HKEY_CURRENT_USER\Control Panel\Mouse, item named MouseHoverTime, specifying the time to pop up in milliseconds (400 milliseconds is the default).

AFAIK, there is no way to control the info pop-up delay without rewriting Windows. The Registry switch for the feature is at Computer\HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced, ShowInfoTip.

There might be some features in Windows Ease of Access settings that affect the delay of the info pop-up, but they would likely increase it.

There is a value ExtendedUIHoverTime, but that seems to be only for the delay for the preview of an item in the Taskbar.