Avoid the Bullet Bills
Python, 72 68 66 bytes
We can ignore left/right - if we assume it's always pointed at us we'll always take the right action. Then if our assumption was wrong we did a useless jump/duck, but that doesn't matter - we'll still be safe.
Similarly, there is no incentive to do nothing. Rather, it's shorter code to always duck, and jump when necessary. Ducking will only be unsafe if the bullet bill is exactly one above the block we're standing on. In that case we will take our x position, bullet bill's y position, take the absolute difference, divide by bullet bill's speed and jump 0.2 seconds before that.
lambda a,b,_,s,x,y:[&quot;duck&quot;,&quot;jump &quot;+`max(0,abs(a-x)/s-.2)`][y+1==b]

Call like this:
f=lambda a,b,_,s,x,y:[&quot;duck&quot;,&quot;jump &quot;+`max(0,abs(a-x)/s-.2)`][y+1==b]
f(5, 1, &quot;left&quot;, 2.5, 0, 0)