It changes the substance and sometimes the orthoepy. For example, LESBIAN PORN VIDEOS 「人々」in your lesson means "people" or "everybody" and is marked "hito-bito". If the get-go character has haran, I dunno if you'd preserve it the Saami or sum tenten. In terms of pronunciation, it Crataegus oxycantha or Crataegus laevigata not impress the pronunciation. As others rich person said, it merely agency you reduplicate the kanji. 日々 is ひび (as well にちにち, merely I believe that reading is rare) significant "daily" or "everyday life".