Like Ozark says, all the work has been done with extract, yes all the rests are done with mashing all-grain. Extract is 100% ready to reconstitute and boil... just like a can of condensed soup.
Here's how you can think of the (extremely simplified) overview...
1. Raw grain is sprouted to create enzymes and dried to create malted barley...usually called base malt
2. That malt may be treated further by the maltster to create specialty malts that are toasted or allowed to convert to create sugars
3 Quantities of base malt and specialty malts are milled and mashed - held in water at a certain temperature to release the enzymes and turn the starches into sugar
4 More water is added to rinse the sugars from the malt and all that mash water is collected as sweet wort
5 That wort is concentrated by boiling...
...If we start with grain and mash it, we boil it down for an hour or so with some hops and it's ready to make (all-grain) beer
or...
...it can be concentrated so much that it makes malt extract syrup or can be dried into dry malt extract for us to buy and we skip the mashing process. In that case, we add some water back in to get the proper sweetness, boil it just as long as it takes to infuse some hop flavor and bitterness and then it's ready to make (extract) beer.
When you get a little further along with extract brewing and want to add steeped grains to increase body and head retention, that starts to be similar to mashing but that, is simplified. Even then, you don't worry about rests at different temperatures because it involves specialty malts that are designed to be used without fully mashing.
Hope that's helpful.