I am attending my bosses's daughters bat mitzvah and I'm not sure what is appropriate to give as a gift. I was thinking just cash or gift card like I would do for any other birthday party I would go to for a child but not sure if that's acceptable as a gift in this setting. I'm not jewish and this is really my first real interaction with jewish faith so anything that would help would be great. Thank you!
In the circles in which I travel (American, generally modern/centrist Orthodox), there aren't any particular restrictions on acceptable gifts for a Bat/Bar Mitzva. The types of gifts I've seen most frequently are money, gift cards, Jewish books, and Judaica objects, but I've also seen other kinds of gifts that one might give a young adult of that age on a formal occasion.
For someone coming from outside the Jewish community, money is certainly a safe bet, given its supreme fungibility. Gift cards are almost as safe, provided that they're to stores that it would be appropriate for the celebrant to shop at (e.g., not non-kosher restaurants and not stores that deal primarily in materials that wouldn't be considered appropriate for young adults in the celebrant's community/family). If you're interested in doing something more personal and Judaism-oriented than money, I would recommend visiting a Judaica store or Jewish book store and asking for recommendations. Also, as I said above, general formal-feeling gifts that one would give a young adult of that age are fine, too.