This is one of many commercial versions of the free SPICE program from the US university at Berkeley.
Each commercial version has some added user shells. The H version has more user selected parameters for the convergence methods. Therefore it is more powerful in the hands of a skilled user but more difficult to learn to use.
HSPICE is generaly used for IC layout design.You can use it for ASIC design.For example you want to realize a circuit on-chip and you have a schematic .By usind gate,metal contacts and silicon you can design that circuit on a single chip by arranging w/L ratios or other parameters.