I always wondered about this. You have guys from around the world playing on club teams together. Some from Japan, Portuagul, Italy, France, etc. What do they do when they are all on the same team? Do they learn the language of the country their club is in? Or do they just all learn english since it is more universal and supports a wide spectrum of users? Any thoughts?
Most players make an effort to learn the language of the country they're in, but on the pitch I think it's just basic commands, pointing, shouting. You can usually tell what somebody means with a few hand gestures. Plus they probably have sentences used in training by the manager, that indicate certain instructions, learned beforehand.
for me, the more interesting and troubling question is how do referees communicate with the players? in league matches, no problem -- whatever the national language is. but what about internationals, especially the WC? I remember a very funny remark from the commentators in the WC66 final. The germans were complaining about the controversial goal -- did it go over the line? -- and the announcers said, "The Germans are complaining, but the referee only speaks Russian and Turkish."
I waould say learn the language that the manager speaks, if not english. He is the one shouting commands from the dug out and trying to rally players!