speak (one's) language
To say something or communicate in a way that aligns with one's preferences, desires, motivations, etc. A: "Look, I know all this technical jargon is pretty boring. Why don't we finish early for the day and go out for pizza?" B: "Oh yeah, now you're speaking my language!" A: "I'm a little worried about pitching my idea to the board of directors tomorrow." B: "Just focus on how your plan will boost profits, and you'll be speaking their language."
speak someone's language
Fig. to say something that one agrees with or understands. I gotcha. Now you're speaking my language. Mary speaks Fred's language. They get along fine.