Dofollow is simply the default state for a link. In another way, any link without the nofollow attribute is a dofollow link.
When another website links to you with a standard (aka dofollow) link, it can directly affect search engine rankings. because this link passes link equity from the linking page.
Nofollowed links are the hyperlinks with a rel=“nofollow” tag in HTML code of the link.
These links do not help you in the search engine rankings of the destination URL because Google does not transfer link equity.