What did the Schlieffen plan call for Germany to do

In WW1, Germany was sandwiched by France and Russia, so theoretically,  Germany invades through Belgium to go around the French fortifications on the Prussian-Franco border (also because Belgium has like no mountains while the French border is literally a whole mountain range). After going through Belgium, the Germans will flank and go behind French lines, completely catching the French off guard and destroying the whole French army.

This will happen while Russia is still bringing soldiers over to the German border and producing weapons and stuff, which is hard for Russia because Russia is big; specifically, Russia has barely enough railroads to bring soldiers, doesn't have enough ammunition or weapons, has horrible leadership, and is on the brink of a civil war that will kill every single person that is at least 0.0000000001% related to the king. Basically, since Russia is just a military, political, and societal mess in general during the 20th century, the Germans believed they could deal with them later after the French.

This however, would have to ensure that the British didn't join the war after the invasion of Belgium, and that Austria Hungary and the Ottoman Empire were decently better than the Russians were they to mobilize faster, which seems pretty easy, except it was hard since Austria Hungary and the Ottoman Empire were shockingly worse. The Germans also couldn't slow down and dig into defensive positions; they had to aggressive take over France within weeks. The Schlieffen plan would ultimately fail after everything I said in this paragraph didn't go the Germans way. Britain joined the war, Russia won a few battles vs Austria Hungary and the Turks on the eastern front (causing Germany to put german soldiers on the eastern front and making the western front forces weaker), and Trench Warfare happened.