"Many children are here."
Translation:Mnoho dětí je tady.
This has to do with Czech numbers. MNOHO is not a number per se but since it defines quantity, it behaves in a similar way. Mnoho, málo, trochu... all description of amounts behave as number 5 and up.
More on numbers 5 and higher can be found here https://www.duolingo.com/skill/cs/Numbers-2
More on numbers 1-4 can be found under Numbers 1
"the most important new information," okay, interesting. i think i know what that means maybe? in this sentence "here" is kind of emphasized? (i think i remember learning that words like "tady" go at the beginning of the sentence. maybe it was only circumstantial to some sentences i was working on months ago and now there is no way to remember :/.)