When you are working with people, either as a co-worker or as a manager, and you have someone explaining something to you that either you don’t understand or you think is outlandish, you need to hide these emotions from your body language.
Not that you need to just accept whatever people are telling you. Sometimes people are confused, inexperienced, or just plain wrong. You can still work with these people and either get them on your page, on your side, or they might have insight you have not yet considered.
But when they are explaining it to you, be careful what you are broadcasting. If they see something in your body language that tells them that you think they are stupid or a waste of your time, they may not want to work with you anymore, or they may actively work against you.