I need to know what is the name of this valve that is for my outdoor water line and where can I get a replacement?
It probably does not matter what type valve it is. Looking at the part you show, I do not thing that you will be able to repair the existing valve, or be able to find parts to do a repair. I would replace the valve with a name brand, top quality, American made valve. You could use a gate, globe, or a full port ball valve. The part you show looks to be from a rising stem gate valve, but I could be wrong. I would have to see the whole valve to be sure.