Calculate the net force needed to give an acceleration of 0,5m/s to a trolley with a mass of 1,5 kg

Use F = ma

It is one of the most important formulas in physics and engineering

With mass (m) in kg and acceleration (a) in m/s^2, the computed force F will be in newtons.

Your units for acceleration should be m/s^2, not m/s. Perhaps someone made a typing error.