This constraint is a specialisation of the more general count/4 constraint, with the (#>=) relation, i.e. the occurrences of V is greater than or equal to N. Note that the order in which N and V occur in the constraint are swapped with respect to occurrences/3 and count/4; this is for compatibility with the argument order in IC (for atmost/3).
ConsistencyModule is the optional module specification to give the consistency level for the propagation for this constraint: gfd_gac for domain (generalised arc) consistency. Note that if V is a domain variable, then the propagation is weak, achieving neither domain or bound consistency until V becomes ground.
This constraint is also known as atleast in the global constraint catalog, where N is restricted to an integer; the more general count/4 constraint is also known as count in the global constraint catalog, and the constraint is implemented using Gecode's count() constraint.
[eclipse 2]: N :: [3,6], atleast(N, [3,A,3,5,3,3], 3).
N = 3
A = A{[-1000000 .. 1000000]}