Néhány means "some, a few, several" in the context of being plural, not singular. So, if we already have a word telling us that it is plural, why bother adding a -k? Gyerek is singular by itself, but in this sentence there's a néhány showing that it should be taken as a group of things and not only one of them.
Native Hungarian here, skahmed is mostly correct
Kennen/connaitre/conocer/conoscere : Ismerni valakit- to know a person
Tudni + inf - to know to do sg= can do sg
Tudok olvasni - i know how to read/ I can read
Tudok úszni - I know how to read / I can read
Tudok angolul - I know how to speak English (= Beszélek angolul - i speak English )
Tudod hogy esik az eső? Tudom. Do you know that it's raining? I do.
Tudod hány óra van? Tudom. Do you know what time it is? I do.
Tudom a verset. - I know the poem. ( I have committed it to memory)
Here they can be interchangeable: Tudom / ismerem az utat. - I know the way.
Hm, am I the only one who thinks tudok+inf is completely accidental and doesn't have a "know how" connotation at all? "I know how to read/swim/speak English" would be "Tudom, hogy kell olvasni/úszni/angolul beszélni." If I know how to drive a car but I can't actually drive, it would be unfair to say "Tudok vezetni" and one should rather say "Tudom, hogy kell vezetni". It's clearly about capability in my opinion.