The question assumes that translation is the proper way to learn new vocabulary in a foreign language. Historically, this habit comes from learning vocabulary lists that had one language (typically the target language) in the first column (i.e. the left column in books for speakers of a language written from left to right) and one or more translations in the target language in the other column.
Whether you go from target language to source language (i.e. Arabic to English in the question) or source language to target language depends on the direction one should eventually be able to translate. When I was learning Latin at school, we only need to be able to read Latin texts and translate them into our native language and never translate texts into Latin. In that case, the direction Latin to native language was sufficient and learning vocabulary in the other direction was a waste of time.
However, when learning a language that you want to be able to speak, you don't want to be slowed down by mentally translating from your native language into your target language. Instead, you want to be able to move from the concept to the foreign term, which should be quicker. For this reason, Gabriel Wyner (author of Fluent Forever) recommends using images on the "front side" of flashcards and the foreign term on the other side. See Gabriel Wyner's Anki tutorial on YouTube: Anki Tutorial 2 - Adding your first pictures from a Frequency List. Since the video dates from 2012, Anki's UI has change a bit but the method Wyner describes can still be used.
For abstract concepts where images don't work and for grammar patterns you can use cloze tests. (For grammar, see my answers to the questions How can I put grammar rules into flashcards? and Creating flashcards for grammatical rules that requires a few steps of thought, such as SPOCK versus WEIRDO. These tips don't rely on translation, either.)