Question

This is a bit of code from Twitter Bootstrap

.navbar .nav.pull-right .dropdown-menu,
.navbar .nav .dropdown-menu.pull-right {
  left: auto;
  right: 0;
}

So from that what does .nav.pull-right mean? (note that there are two dots)

I have searched here because I assumed it was some kind of selector but I couldn’t find it.

Answer 1

The two dots indicate two classes.

I.E. It is selecting all elements with a class of nav AND pull-right
it’s target HTML would look like this

<div class="nav pull-right"></div>

it doesn’t necessarily mean that it’s looking for a div either. It could be any element.

According to your selector in full, it would match something like these
.navbar .nav.pull-right .dropdown-menu, .navbar .nav .dropdown-menu.pull-right

<element class='navbar'>
    <element class='nav pull-right'>
        <element class='dropdown-menu'>It would match this!</element>
    </element>
</element>

as well as

<element class='navbar'>
    <element class='nav'>
        <element class='dropdown-menu pull-right'>It would also match this!</element>
    </element>
</element>