The velocity of a projectile at the initial point A is$\left(2\widehat{i}+3\widehat{j}\right) m/s$. It's velocity (in m/s) at point B is

$\overrightarrow{\mathrm{u}}=(2\hat{\mathbf{i}}+3\hat{\mathbf{j}})\mathrm{m}/\mathrm{s}$

Horizontal component of velocity of projectile remains same while the vertical component of the velocity gets reversed with equal magnitude at the time of strike to the ground.

$\begin{array}{rl} & v_x=u_x \text{and }{v}_y=-u_y\\ & \Rightarrow \overrightarrow{v}=u_x\hat{i}-u_y\hat{j}=(2\hat{i}-3\hat{j})\mathrm{m}/\mathrm{s}\end{array}$