To put a hold on something means to prevent or stop something from happening or to delay something. If you put a hold on a project for example, it could mean to pause or delay it. This is a phrasal verb that is used in both social and professional contexts.

1. The bank messaged me to say that they are putting a hold on my account due to recent suspicious activity.
2. I really wanted that book, so I asked the library to put a hold on it for me so no one else could take it out before I got there.

1. We will have to put a hold on the deal until these legal complications have been ironed out.
2. Our shaky financial situation means that we are putting a hold on hiring new employees for the time being.