Kyoto and other places in Japan have been inundated with tourists in the last couple years. I live in Japan and have been to Kyoto at least a dozen (probably closer to twenty) times in the past twenty years, and going back this summer I could not believe how many foreign tourists there were from elsewhere in Asia, Europe, etc. etc. On one popular street in Gion, the only Japanese people I saw were the guy I was with and a delivery driver. Pretty much the same thing at some temples. I spent three days in Kyoto (taking my visiting family around) telling them I couldn't believe how many foreigners there are. Of course they had nothing to compare with so....
Japan needs the tourism money and this influx of tourists is great in that respect. It's also great because maybe it will get a few more people to see the utility of studying in English and help lead to improvements in the horrid way English is taught here. At the same time, the surge in foreigners is pretty overwhelming, I'm sure, for the folks that live in any touristy areas. (I'm amazed at the increase in tourists in Yokohama, where I live, over the past few years, and I'm on the edge of Tokyo.) And it's undoubtedly leading to some awkward situations and problems because of cultural differences.
This poster is just Kyoto trying to cutely remind visitors that customs are different here. In the past, many/most travelers got guidebooks and read all about cultures before they came, at least on the plane ride over. Now I think most people just try to wing it with Trip Advisor and whatnot. That makes it that much less likely that people are going to get the behavior tips they need. Typos notwithstanding, this is cute and friendly, not rude—or at least that's clearly what they're going for. And it's not overkill. Some folks clearly need it.