a hundred of year / a hundred years

"a hundred of year" is wrong; you should say "a hundred years"
e.g. They can live for one hundred years. Please pay attention "years" and not "year"!

In some occassions, we will use "of". For example, "a lot of", "a couple of", "plenty of".
e.g. There are a lot of books. It takes me a couple of hours to finish the homework.