I'll have to make some assumptions here. First, I'll assume that the length of one side of the base is 2 and that the altitude (height) is 3.
The area of the (square) base is 2^2=4. The area of ONE triangular side is
A=(1/2) b h; here that comes out to A = (1/2) (2) (3) = 3 square units.
The total area of the four sides is thus Atotal = 4(3 square units), or 12 square units. Add this to the area of the base (4) to obtain the total area of the prism: 12+4=16 square units.