$u=Intitial \; Velocity \newline v= Final\;Velocity \newline t=Time\;Interval \newline s = Displacement \newline a=Acceleration$

These are only valid when acceleration is uniform

1. Final Velocity = Initial Velocity + Acceleration * Time

This is pretty simple, you have some initial velocity, and for every second you're increasing the the velocity by the acceleration.

2. Displacement = (Initial Velocity * Time) + Half of (Acceleration * Time squared)

Why?

3. Velocity squared - Initial velocity squared = Double of (Acceleration * Displacement)

Again, IDK why