when you go to type numbers into the boxes for anything, like where you would set a private variable or check a value (like where the red arrow is pointing), you can double click an object's icon to get a list of expressions.
If your object is using physics, there are Get Velocity X, and Y expressions. Although they aren't in pixels per second, it's physics's internal scale of speed.
if you need to combine these two into one speed, it would be
if the answer must be in pixels per second, then you would have to make a LastX and Last Y private variable
-----Set LastX to sprite.X;
-----Set LastY to sprite.Y;[/code:ayxlwcfm]