It's way to describe controlling a conversation. It might involve things like changing the subject to something one person wants to discuss or asking a lot of questions to keep the other person on the defensive.

To steer means to guide or direct. For example the steering wheel in a car guides and directs the car. Steering a conversation means directing it toward more desirable topics or easier topics to discuss or objectives to be reached during a conversation. The classroom discussion got off the subject very quickly. The teacher carefully steered the conversation back to the objective of the lesson.

If it went into a wrong direction you might want to 'steer' it in the direction you like. If you are in a business meeting talking about cats .. you might want to steer it.. "Steering" something means controlling which direction it moves in. For example, you steer a car when you drive. We also use the word "steer" to talk about controlling a conversation. You steer a conversation when there's something that you want to talk about, or something that you want to avoid talking about. For example: When people bring up politics, I usually try to steer the conversation back to something a little less controversial. If you'd like to return to a topic that you were talking about earlier, you "steer the conversation back" to that topic. I hope it helps.