A family of Microsoft word processing software products for creating web, email, and print documents.
The Bilingual Dictionary feature offers a few more languages but even that won't help for Arabic.
Right-to-Left scripts are not supported in Mac Office. Although the characters can be displayed they do not "connect" as required so virtually everything is misspelled & incapable of being corrected, making proofing tools for those languages pointless.
I'm not sure which direction you're trying to translate, but if you paste an English word or phrase into a blank document you can use the Translate feature in the Reference Tools pane to access the online translation service. That may satisfy an occasional requirement but not for frequent use & I'm not sure how well it will work in the Arabic-to-English direction. If you need to work in RTL scripts you'll need to use a word processing program that supports it such as what's suggested in the links provided by Ty_hell_heaven. Other discussions are available as well if you take advantage of the Community's Search feature using terms such as arabic.