Objection handling refers to addressing and overcoming customer concerns or doubts to persuade them to make a purchase. It involves providing answers and value to alleviate objections and move the sales process forward.
Onboarding involves introducing your solution to a customer and helping them get ready to use it post-purchase. It can also refer to the process of hiring and training a new sales representative.
While each company follows its own methods to establish the criteria for identifying an opportunity, essentially it refers to a qualified lead that Sales is actively engaging with.