When a sailor is learning his or her job, one responsibility that person must learn is how to adjust the sails on the ship. The sails are large pieces of cloth that use wind to move the ship along, and the sails are made taller or shorter, and moved from side to side with ropes. If a sailor doesn't understand how the ropes work, bad things can happen. A ship can crash, or worse, become lost in the ocean.
If someone is going to show you the ropes, it means that they are going to show you how to do something. It’s common that a person new on a job will need to learn new tasks and skills, or even where to find things in the office. That’s all part of learning the ropes of a new position. You have to be aware of what’s expected of you and know how to handle your new responsibilities.