My 20 year old son is in a relashionship 6 months and announced that he wants to get engaged.He has no job isn't being specific about what he wants for his future (EDUCATION).We have had until this relashionship very good communication between us.He wants to move in her home and her parents are in favour despite the fact that we as his parents do not agree.
Please I would appreciate an answer.

Well, he's 20 years old and has to make his own decisions. I agree that there should be some sort of career path established before he makes such a commitment. And I question the wisdom of his intended in-laws simply allowing him to move into their home with no visible means of supporting their daughter. You can discuss your concerns with him but don't fight or argue with him. Support his decision even if you don't agree.

I would consider taking this a few steps further.

Stop supporting him. I presume right now he is living at home, enjoying all the benefits of being taken cared of financially and otherwise.

Let him know that the moment he moves in with his girlfriend, you will have considered him moved out- for good.

No loans, no bailing him out, no car, etc.

If he wants to be a man, he's going to have to sort it out with his girlfriend, and her parents. Once he leaves your home, you have to presume that he is capable of making it on his own, regardless of what choices he makes.

Don't let him think that he has options here, and can use them as he feels like it. When he moves out, he moves out. End of story.