Welcome to the forum. Perhaps the best advice (before spending
any money!) would be to try and have a chat with her photography teacher and find out what cameras they mainly use at the school. The 'big two' makes of traditional DSLR type camera (which is probably the type of camera most widely used for school photography lessons) are Canon and Nikon. However, they have different menu systems to select different settings, so it can be a bit confusing if the school and most of the other students have Canon and one or two others have a Nikon, or vice versa.
Mirrorless type cameras are gaining popularity these days (with Sony seeming to be well regarded), so ask the teacher if they're mainly using DSLR or mirrorless. While the general principles of photography remain the same with both these types of camera, mirrorless offers some features that DSLRs don't have, so once again, if most are using one type of system it can be a bit confusing to someone who's using the other.
As to which make of camera, you can't go far wrong with either Nikon or Canon for DSLRs, even their cheap(ish) entry level cameras will give good results these days. If the school doesn't use one or the other, then a Canon DSLR will probably give you access to a wider range of more economically priced lenses than Nikon, Canon's menu system is reputed to be a little more user-friendly too. Don't rule out buying a used camera in mint-ish condition from a reputable dealer such as
MPB or WEX, as you may well get better value than buying brand new (but do check for any special offers on new cameras and camera kits first, as these can sometimes be better value than buying used!).
Don't go mad price wise either, particularly if the 14 year old in question is a bit on the accident prone side - it's a shame to break something really expensive... or find it not being used as she's decided photography isn't for her after all. You can always upgrade the camera when she's older and you're sure it's going to be money well spent!
Don't forget to allow some budget for a couple of different lenses and a flash unit too - hopefully, the photography teacher should be able to give you some advice on what to get, and when. Once again, buying used from a reputable dealer can save you money when buying accessories. If your 14 year old takes to the subject and enjoys it, then birthday and Xmas presents can be a good opportunity to buy additional kit.
Once you've narrowed your choice down a bit then come back to the forum and ask advice on which model to buy. You'll probably get a few different answers, as people have individual preferences, but it should point you in the right direction. Hope this is useful.