1) "Linear speed sensor" is the correct name I will update the text
2) Pitch is how the bow of boat or plane is pointing up or down. For boats pitching up gets some of the hull out of water for possibly more speed (design dependent) while big ships tend to want a pitch of zero. Zero pitch is level.

and i have one more question what is the pitch control?

What is a motion sensor because it does not exist in stormworks is it a tilt sensor or are you talking about a speed sensor?

Link to alternate mk 3 that uses the reverse gear rather than linear motion. Linear motion can be set using select to a directional value but the default absolute had led to some confusion.