Wiktionary
n. (context idiomatic management English) A payment offered to an employee as an inducement to join, especially if currently working for a competitor.
Wikipedia
A Golden hello is
1. a generous welcome package for new employee from a rival firm to entice the employee to leave the competing company. A payment made to induce an employee to take up employment. Unlike a signing bonus, a golden hello is more likely to be extended to executive-level employees than to lower-level employees.
2. a payment from a government to an employer who takes on new staff when jobs are hard to find in a recession.
3. is more like financial incentive for graduates in STEM (science, technology, engineering and maths) subjects into teaching, in the UK.
Usage examples of "golden hello".
The man needed his outfit's first op to be a success, and therefore needed to secure a few first-rate personnel in a hurry, so the money was kind of a golden hello.