я попытылся, как мог, на ломанном английском... но не смог записать коммент у хозяина того журнала, поэтому пишу здесь. если у кого-то есть желание дополнить, то вэлкам, лучше, конечно, по-английски... но можно и так.
a bit of context: the is a classical, almost archetypical, poster (and slogan) of the soviet times. by the style, and content, it is from the 1920-s, may be 1930-s... although i can imaging its usage later on too, as a retro style. could be also quite a recent remake, since these things are getting popular lately. one has to judge its age by the quality of paper.
the slogan literally says "all [=everybody] to the communist subbotnik"... i guess, though, that foreign people would need a bit more explanations here : ))
grammatically, "Vse na..." means here "let's all go to...", may be with a slightly more demanding voice, and not just as pure invitation.
on the poster it is a voice of the "worker", a proletarian, who's calling others to join him and go to this "subbotnik"... but it could be also read as a voice of the party (= lenin) who's calling people to go to this event.
now, what's subbotnik: it's from russian "subbota", saturday. but it later became a special word, meaning a free and theoretically voluntary work, usually for the benefits of your country (city, street etc).
it was introduced in the 1920-s, and was used as a tool to mobilize free labor to do certain work, in their spare time (often during the weekends, so the name). actually, it was never too voluntary...: ((
most often "subbotniks" were used for cleaning streets, or the factories, or even offices, most often around the spring time. however, it could be also used for other reasons, like to collect paper scrap from the homes ("makulatura"), or metal scrap from the streets ("metallolom"), both being "favorite" sports of the soviet "pioners" (= members of the young communist union).
there is a famous painting (don't remember the painter, will put the referrences here later), of lenin himself participating in such a subbotnik and cleaning the territory of kremlin, thus showing good example to all people.
thus, these "subbotniks" were also called "leninskiy"... in addition to "kommunisticheskiy", or communist, with the meaning that they are called by the communist party, but also they all contribute to the building of the future communist society.
later in the 1970-s and 1980-s these "subbotniks" became ritualistic activities, usually run once in year, during the spring, and most often around april 22, the date of lenin's birthday. schoolchildren cleaned the gardens and territories around their schools, and people in general could clean streets, often very dirty after the winter, or their own offices (all for free).
these posters were therefore hanging up before the event, and served as "advertising billboards" to let people know that such an event will happen.
this is in brief what's it's all about... please, fire questions if you need more explanations :)) these memories are still quite alive, but getting rusty with years...