What does "Dofollow" mean?

Dofollow:

Dofollow is the default relationship of any link. In fact, there IS no "dofollow" code; "dofollow" or "follow" is what happens to a normal link. Google follows that link and assumes that you are endorsing the recipient of that link because you linked to it. (See TrustRank).

This is an example of a "dofollow" link:

<a href='https://www.heifer.com'>Donate a Goat to Someone in Africa</a>

Note that there IS no "'dofollow" relationship noted -- because that's what Google does unless you tell it not to follow the link with Nofollow code.

 SEMRush: Nofollow vs. Dofollow