Let me explain it a little better. Here’s your code (minus all button code):
<h1 class="headingName">Brian Moreira</h1>
This is important: Think of anything between a opening tag and its closing tag as its scope.
All the tags within that scope are its descendants (i.e. children, grandchildren, etc.), and all outside that scope would be its ancestors (i.e. parents, grandparents, etc.) It’s very much like a family tree.
So your buttonSpacing div and the h1 headingName are both children of the container-fluid div. The h1 is the sibling of buttonSpacing. The buttonSpacing div is the parent of the row div. If your buttonSpacing div was somewhere in between the opening h1 and closing h1 tags, then it would be the child rather than a sibling.
When code is tabbed nicely, the relationships are easy to see. You actually did a great job of that in your code. Siblings are on the same tab, children are tabbed more (so further right), and parents are tabbed less (so further left).