There are 6 faces to the prism:
2 each of (Length x Width): 2(4 x 4) = 2(16) = 32 m²
2 each of (Length x Heighth): 2(4 x 8) = 2(32) = 64 m²
2 each of (Width x Heighth): 2(4 x 8) = 2(32) = 64 m²
The sum of the faces is the Surface Area (S.A.)
32 m² + 64 m² + 64 m² = S.A.
160 m² = S.A.