usage of this pointer in std::bind

I was trying to read and understand std::bind when I stumbled on below answer:

Usage of std::bind

I see one statement like below:

auto callback = std::bind(&MyClass::afterCompleteCallback, this, std::placeholders::_1);

I am unable to understand what is the usage of 'this' pointer and when one should make use of it? 'this' pointer means the current object address itself so it would something mean that 'use this object' - if so how can I use the same statement outside the class still having the same meaning?