There's a trick to pluralisation of strings so they can be translated (see also [translating](http://projects.theforeman.org/projects/foreman/wiki/Translating#Translating-for-developers)).  You'd write this as:

    n_("%s VM associated to a host", "%s VMs associated to hosts", count) % count

(singular, plural, count and then the % replaces the %s with count in the resulting string)