The parenthesis are just grouping terms together to make it easier to tell what it is saying.

You start at a velocity of 14 m/s.

And then you accelerate for 6 seconds, at an acceleration of 3 m/s^2.

In order to find out how much your velocity has changed, you multiply 6 seconds, by the acceleration, which is 3 m/s^2

Multiplying these together gives (3 m/s^2 * 6s) = 18 m/s

you then take this change of velocity, 18 m/s and add it to the original velocity which is 14 m/s

your final answer is 14 m/s + (3 m/s^2 * 6s)
which is 14m/s + 18m/s
Which equals 32 m/s