Elena, this doesn't make much sense in English. Knowledge of what? HAVE KNOWLEDGE usually means быть в курсе дел(а).

Then "to get (basic) knowledge"?

Paraphrase it for me, yes? What is it referring to?

It means that children should get some primary education before going to school

At home or in a structured setting like daycare?

It doesn't matter, just they must know something like reading, counting...

May be "to acquire knowledge'?

They must have learned some of the basics before entering school.

Present Perfect? It's because it means "by some moment"?

Yes, BY THE TIME they enter school

Interesting! Thank you!

Add your translation)

Thank you 😊

My mutual thanks 🌝