Hey, maybe you’ve got confused with the Japanese in the title?
日本語上手 is 日本語（Japanese language）+ 上手（good, skilful） and it’s the standard way Japanese folks will use to praise your Japanese
日本語上手ですね！
Your Japanese is so good!
And as any foreigner who has ever spoke one single word in Japanese in Japan (be it Arigato or whatever) will promptly tell you, Japanese people are famous for praising absolute anything you say (or write) in Japanese, no matter how elementary it might be. That led to a running joke in the Japanese learning community about how getting 日本語上手d actually makes you feel worse, lol.
That aside, Sign Languages in Japanese are referred as 手話. So you have アメリカ手話、日本手話、etc.
If you wanna talk about those be more than welcome! There have been a couple topics about it over the years, I think this is the most recent one.