You are so talented. Haha, I use this all day, so I know giustificazioni delle assenze is used to prove why you didn't come. I am a school book called LIBRETTO PERSONALE, which says which day I didn't come, why I didn't come, and then I need my parents' signature. If your city is an adult, in fact, you don't need to write MOTIVO DEL SALUTE when you are sick, and MOTIVO FAMIGLIARE when you are in trouble, which means something is wrong at home.
è rimasto assente nei giorni is not easy to explain. This sentence should be followed by a space or a word and then a space. This is the day for you to write down that you didn't come with spaces. If you want to write two days when you didn't come, fill in one.