The phrase “in Arabic language” in Arabic is more naturally:

في اللغة العربية

So there are two common expressions:

باللغة العربية = “in Arabic” (used for language labels like “write in Arabic”)

في اللغة العربية = “in the Arabic language” (literal wording of your phrase)

If you’re just labeling a language (like on menus, apps, or forms), باللغة العربية is the most common.