Ask HN: How do you learn to speak the other person's language?

A year ago when I was a developer at a big bank, I found that I had to speak to the desk I worked for in their language. I.e. I had to know enough finance to have the conversation in terms of stocks, bonds, options, etc...

Now, I'm on the other side of the table and I find that I need to talk to development guys and I find that I end up talking to them in terms of servers, databases, queries, algorithms, etc...

I also end up talking to our lawyers a lot and I find I need to understand legal talk which they are rarely willing to convert into "plain" English (for fear of losing precision I think).

During all this time, I've found that I struggle for some time to "speak the other person's language."

Any advice? I'm sure it comes up a lot for people here who have to talk to customers.