The feature is called "hyphenation", the option is Tools > Language
Hyphenation for existing text boxen and in Tools > Options for new text
boxen. This is not the correct group for your question; for questions
about Publisher not relating to writing programs in or using it, the
correct group is microsoft.public.publisher (unless you are doing
prepress or webdesign work, in which case the correct groups are
.prepress and .webdesign respectively).