This app was mentioned in 4 comments, with an average of 2.50 upvotes
Welcome to Ukraine!
You can buy prepaid SIM card and get mobile Internet access in a minute. It's cheap ($2-3), so later you can simply throw it away. SIM cards are available in food stores, kiosks and many other places.
3G coverage by all major operators (Kyivstar, Vodafone, Lifecell) in Kyiv is more or less the same.
If you really need offline dictionary, then try this
It has only Russian dictionary, but in Kyiv (sad to say) it would be hard to find menu in restaurants or other information in Ukrainian. Unless this is some official information.
Here is an offline dictionary app.
https://play.google.com/store/apps/details?id=fr.nghs.android.dictionnaires
You can download French or English-French dictionary. The free version allows you to download more than one dictionary after looking for an ads.
For translations/dictionary for myself, I often use the app Offline dictionaries https://play.google.com/store/apps/details?id=fr.nghs.android.dictionnaires&hl=en It has a bunch of different dictionaries (anagrams, synonyms, etc.) that you can download in a bunch of different languages. And it has translation dictionaries too!
Offline Dictionaries. It's simple to use, plenty of dictionaries to download and it has a bookmark feature! (I finally found one without a spam of pop-ups and ads)
https://play.google.com/store/apps/details?id=fr.nghs.android.dictionnaires&hl=en