A ship is moving at a speed of 56km/h. One second later it is moving at 58km/h. What is its acceleration?

Here the term speed is used in the same sense as velocity.
Initial speed or velocity, u=56km/h =m/s  = 15.55m/s
Final speed or velocity, v, = 58km/h  = m/s = 16.11m/s
Acceleration = a=? (to be calculated)
Time, t = 1s
Now, putting these values in the first equation of motion:
V=u +at
We get:16.11 = 15.55 + a x 1
a=16.11-15.55 a = 0.56m/s²
Thus, the acceleration of the ship is 0.56m/s².