Windows · Open the properties of the item

Files

Windows · Linux

Alt+Enter

Mac

Not on this system

Opens the properties window of what you selected — size and dates for a file, free space for a drive.

Win-key combinations are captured before any program sees them — nothing can clash with them, and nothing can override them either.

Reading the key names

Keys joined by + are pressed together: Ctrl+Shift+P means hold Ctrl and Shift, then P.
On a Mac, Cmd is ⌘, Option is ⌥ (labelled Alt on some keyboards), Control is ⌃ and Shift is ⇧.
Windows Ctrl usually becomes Cmd on a Mac, but not always — this reference lists both combinations separately.
With a Korean, Japanese or Chinese input method active, shortcuts built on letter keys may not fire. Switch to Latin input and try again.
When a combination does nothing, another program has often claimed it as a global shortcut first.

Q. What is the shortcut for Open the properties of the item in Windows?

Opens the properties window of what you selected — size and dates for a file, free space for a drive. It is Alt+Enter on Windows and — on a Mac.

Q. Is it the same on Windows and Mac?

No — Alt+Enter on Windows, — on a Mac.

Q. How many keys is that?

2 pressed together. The combination sits under Files in Windows.