Super! You can see that from $$4 \, \mathrm{s}$$ to $$6 \, \mathrm{s}$$, Jerry has covered the maximum distance. So, his speed of $$10 \, \mathrm{m/s}$$ was the maximum. During the first and last $$2$$ seconds, his speed was only $$2.5 \, \mathrm{m/s}$$.
Just like velocity tells us how fast an object's position is changing, acceleration tells us how fast the velocity itself is changing. Mathematically, $$\text{Acceleration} = \frac{\text{Change in Velocity}}{\text{Time}}$$.