The velocity of the particle can be found using the work-energy theorem, which relates the change in velocity to the area under the acceleration versus position curve.
Given that the velocity at \( x = 0 \) is \( 0.8 \, {m/s} \), and from the graph, the area under the curve between \( x = 0 \) and \( x = 1.4 \) is the work done,
which contributes to the change in velocity. From the graph, we can estimate the area, which leads to a velocity of \( 1.2 \, {m/s} \) at \( x = 1.4 \).
Thus, the velocity at \( x = 1.4 \, {m} \) is:
\[
\boxed{1.2 \, {m/s}}
\]