What does get on board mean?
Get on board means “to support or become involved in a plan or idea” (e.g., “All of the managers have gotten on board with the employees’ request for remote work on Fridays”).
In this English idiom, “get” means “become,” and “on board” is a metaphor for being on a ship or aircraft that means “in agreement.”
Idioms and phrasal verbs with “get” can be tricky, but the QuillBot Grammar Checker can help you use them correctly in your writing.