it helped me.
If i were to write this as code.
Extends CharacterBody2D
func _physics_process(delta):
# Vector2( 0 , 1 ): is gravity direction
# delta * 980: pixel gravity constant multiplied by the change in time.
self.velocity = self.velocity + ( Vector2( 0 , 1 ) * ( delta * 980 ) )
self.move_and_slide()
I noticed i could have connected the delta from physics process event. But I hope you can see the picture.
Also if you want to work with a single axis in isolation, you can break a vector like this example from the link.
You just have to recompose it back into a vector (make vector from float ) before you set velocity.