LSA (Lateral Surface Area) is defined as the surface area of a three-dimensional figure excluding the areas of the bases.
The lateral surface area in prisms is calculated by simply multiplying the perimeter of the base by the height of the prism. If the base is hard to recognize, then there can be multiple "bases" and multiple "heights". An example is a cuboid or rectangular prism, in which any of the faces can be used as the base for calculating LSA as long as the corresponding height is used. On the other hand, figures such as cylinders just have two bases and one height.
$$ \text{SA}_\text{L}=\text{PH} $$