Idon't understand this question. i tried finding out the measure of s, but i can't tell what 0.4 stands for. it evidently isn't 0.4 degrees. i don't think it is 0.4 of 360 degrees. if someone could i would be really happy. oh yeah and correct answer get brainliest.

That "0.4" most likely represents 4/10 of one radian, which in turn is approx 57 degrees.  This whole problem is about finding arc length:

s = arc length = r * theta, where r is the radius and theta is the central angle in radians (not degrees).

Here you have arc length s = (5 units)(0.4 rad)= 2 units.  The arc marked "s" is 2 units long.