There will be 2 types of backlinks.

They are:

Do follow - It tells search engines to follow the links and it will have a high authority
No-follow - It instructs search engine bots that a hyperlink should not influence the link target ranking in search engines.
No follow links helps in rank improvement. Many people run after Do-Follow links and ignore No-follow links thinking theses will be of No Use for SEO.

The benefits of No-Follow Links are:

They passes Link juices.
Links build awareness and make the user spend more time on our website.
Leads more referral traffic.
Increases more leads.
If one link from another site leads to your blog and internal links to another blogs in your site which increases users engagement.
Increases Google rankings.

Do-Follow:

Backlinks created from high PR (and high Domain Authority) sources will pass on the link juices towards the hyperlinked blog, thereby improving its ranking position among the search engines significantly.

So, when doing search engine optimization it is important to concentrate your link building activities on sources that allow you to build do-follow links. These links will remarkably enhance your link profile and improve your page rank.

Source : benergsoftwaresolutions

Dofollow will give link juice to link. Nofollow will not give link juice to link.

No follow link: In this link google bot won’t crawl the link and won’t pass any link juice.
Do follow link: In this link passes link juice and they definitely help you much, in order to achieve better page rank.