Is there to get the speed of a of en actor in blueprint

HI I,m making a game where you are a cube that is constantly moving forward when you not moving fast enough you die. I need to know the speed of the player for the math port of the BP

You can use the GetVelocity node to get the current velocity of a an actor. The caveat here is that the actor must be simulating physics or have an accociated MovementComponent. If you are moving the actor by other means, you will need to calculate the speed yourself.