We can use the equation for kinetic energy, K=1/2mv². Your given variables are already in the correct units, so we can just plug in the variables and solve for v.
K = 1/2mv² 16 = 1/2(2)v² 16 = (1)v² √16 = v v = 4 m/s
Therefore, the velocity of a 2 kg mass with 16 J of kinetic energy is 4 m/s. Hope this is helpful!