What does it mean "dofollow"?

tag contain a link which link redirect to website.

That is the little addition to the "a" tag in form

DoFollow is actually a slang term that refers to websites that do not use the nofollow attribute in their links.

rel="dofollow" . in any link indicates search engines to follow this link and index and check internal pages for that link .
It will help you index fast on google , get better SERP . And It will increase your links page rank .
nofollow and dofollow both are important to make your link building system look natural .

Do follow means a tag contain a link which link redirect to website.

dofollow means that if the search engine robots visit a website, it automatically will also visit each link is dofollow who were there.

characteristics dofollow link is a link with "a" tag
rel="dofollow"

dofollow - link rel to guide bots whether to follow or not

rel="dofollow" .dofollow means that if the search engine robots visit a website

DoFollow defines links that are not modified with the 'NoFollow' attribute. Learn more about what they mean for your backlinking campaign,
.dofollow means that if the search engine robots visit a website

Do follow means Google crawls your links that helps to increase traffic and rank of the specific set of keywords but No follow means Google does not crawl the link you have given.So, it does not help in getting good rank but some no follow links helps in getting traffic.

My understanding of the do-follow is that it is the default setting of a web page. That means when you post on a web page that is not set to a no-follow then that is a do-follow. Posting your backlink there will get traffic from 2 ways – when the reader of the web page clicks on your backlink and when the search engine crawlers see the backlink and places your backlink on the search list.