Hi, can anyone please tell me what is the majaor diffrence between no-follow and do-follow?

NoFollow:

A link which cannot be followed by bots is called as NoFollow links. But humans can follow them. The bot will read a link and will not come back to that link if it is NoFollow. We use this type of links to tell google that 'don't influence these links'. NoFollow links prevent sharing our URL values(DA,PA) to an outbound link. Only 1 backlink will be created from connected URL.

DoFollow:

A link which can be followed by both bots and humans is called as DoFollow link. Whenever the bot access that link, number of backlinks will be increased.

Most of them think that NoFollow links are not useful. But still this will be useful if it is relevant.