With no call to action, this sign had me a little puzzled. The nearby parking attendant explained that it’s to remind people that there’s a school nearby, with children learning the classic Uruguayan practice they will carry into adulthood, namely wandering around in traffic, oblivious to it. Well, OK, he didn’t say exactly that.
Regardless, assuming that an Uruguayan driver will make the connection between the word niños and the thought that perhaps he should slow down strikes me as an entirely unreasonable proposition.