The easy explanation is noindex means doesn’t get indexed in google. nofollow means google doesn’t give link credit to that pages links.

Examples:

noindex, follow: You could have a page onsite that is noindex (will not show up on google search results page) but google will follow the links out that are on that page.

noindex, nofollw: That page will basically not exist in google and the links on that page will NOT be counted in any way.

index, follow: The page will show up in google and google will let link juice flow from links on that page

index, nofollow: That page will show up in google and the links on that page will NOT be credited with link juice flow.