In Metaobject protocol (MOP)§

See primary documentation in context for HOW

Returns the metaclass object, as in "Higher Order Workings".

say (%).HOW.^name # OUTPUT: «Perl6::Metamodel::ClassHOW+{<anon>}␤»

HOW returns an object of type Perl6::Metamodel::ClassHOW in this case; objects of this type are used to build classes. The same operation on the & sigil will return Perl6::Metamodel::ParametricRoleGroupHOW. You will be calling this object whenever you use the ^ syntax to access metamethods. In fact, the code above is equivalent to say (&).HOW.HOW.name(&) which is much more unwieldy. Metamodel::ClassHOW is part of the Rakudo implementation, so use with caution.