Different agencies and networks have their own brand name for this Russian translations service, but basically the way it works is that you go to the girl's profile on their website, click the "Send Me a Message" button (labeling will differ from site to site), paste your message into a text box, and click "Send".
The agency gets the message, translates it if necessary, prints it out, and calls the girl to ask her to come pick it up. sometimes you pay one flat price which includes Russian translations and the women's replies, sometimes these are extra.
But when you do that you open yourself up to several significant problems.
First, you open yourself up to the possibility of getting stuck with a bad Russian translator/interpreter.
And navigating the translation challenges wisely removes many avenues for Russian scammers.
First I will tell you the all important translation trap to AVOID LIKE THE PLAGUE... If you are communicating with women that you met through an agency or an agency network, you usually have the option of using their agency's "Letter Forwarding Services".
Any professional in Russian translations can basically convert English sentences to Russian and vice versa, but some need to stop you frequently and ask for clarification, some cannot translate humor to save their lives, and some just don't seem to give a crap about their job.
Eventually you will need to use Russian translations if you pursue Russian women who do not know English.
This will be the case whether you are following the correspondence approach or the tour approach.
Second, if you are not really confident in the agency, or if you are just unsure about them, you open yourself up to the risk of being SCAMMED!
Just as written translations have scams described elsewhere, scams are common with live Russian translations as well. Well, just as with the written scams, many agencies recruit HOT Russian women to their site who either do not speak English or who PRETEND to not speak English so that a Russian interpreter is required.