日本語から英語に訳すって英語でなんて言うの？

To say "Japanese to English" we would say, "Translate Japanese to English." Translate is the proper word to mean changing one language to another language. A more infromal way to say the same thing would be, "Change Japanese into English." This sentence says the same thing, but less formal. In a sentences we could say, "I need to translate Japanese into English to understand these directions." or "I need to change Japanese to English to understand these directions."

It is a pretty basic phrase used in most textbooks when learning English.

example:
Please translate the following into English from Japanese.

There are many ways in which you could say this. Conversationally, you might say I am good at translating from Japanese to English." whereas more formally you could use something like"I can translate well from Japanese to English". If writing a resume or cover letter for a job, you may prefer to use the statement "My translation skills from Japanese to English are strong."

To be good at something = to be able to do something well:
'I'm really good at diving!'

When translating from one language to another, it is a real skill to maintain the original meaning whilst making it sound natural and normal. When trying to express that you have good skills, it might not be enough to say that "I am good at translating Japanese to English. A literal word for word translation may sound odd but a skilled translator will be able to respect the original meaning of the text and be able to provide an idiomatic natural translation.

Add the word 'really' for extra emphasis, or you could say 'I am excellent' or 'I'm skilled at...'
'I'm skilled at translating Japanese into English'
'My Japanese to English translation is good'
'I have excellent Japanese to English translation skills'