Classes Help and Understanding

Can somebody explain what is the meaning and function of class= jumbotron or class= container
After reaching challenge 111 , I still don’t understand class=row then there’s -col-xs-15 what does it mean?

The class jumbotron is just a premade styled div (go to the Bootstrap docs).

The container/row/cols part, I sujest you to do those challenges again.
They’ve explained it really well with the background colors and all of that.

Basically the container is a container for all you content. You also have container-fluid that is good for mobile becouse it doesn’t have margin around it.
The row it’s a row… You can have multiple rows on a webpage.
Example: a row for the header (or you can make a separate container-fluid for it) and other for the main section, other for other and other for the footer.
Then the col is for the responsive design. You can have different collums on a row (12 in total). Attaching the -md-/-sm- part is for the breaking points. md witch is for medium screens have their layout. Than you can add a separete col-sm- after the col-md- to have a different layout with smaller size screen.

You can understand this better when you’re making stuff, but I really suggest you to go over that part again.
Also read documentation (MDN, the Bootstrap docs, etc…), because FCC only gives you the basics.