Oh boy, a lot of us real humans have traveled in third world places where no European language was spoken . You always can manage, with your eyes, your hands, whatever . . But in France you'll always find somebody who knows at least a little English, so it's far easier .
Anyway, from the airport there is a public transport to Bordeaux train station, and from there there is a bus line to Lacanau . There are signs in many places, towns names don't change, train is train, bus is bus or autobus, station is gare, and as I said there are people who know enough English to help you .