Tell your friend to check out the Canon USA online store...
https://shop.usa.canon.com/shop/en/catalog/cameras/refurbished-eos-digital-slr-cameras#facet:&productBeginIndex:0&orderBy:11&pageView:grid&pageSize:36&They have some really good deals on refurbished cameras there, but stock comes and goes quickly, so she may need to be patient. For example, they are out of stock right now, but have been offering Canon Rebel T6i with an EF-S 18-55mm IS STM kit lens for under $500. That's a lot of camera for the money. (I'm not knocking the T3i that some others recommended, but that's now a five or six year old model and there have been significant improvements in autofocus systems and image quality in the more recent models.)
Canon "factory refurbished" are typically not much different from new. Many times they're just returned overstock or open box/demo units that haven't seen any real use. They all also have the same warranty as new (you won't get that with other brand refurbs or with used gear).
If she considers this suggestion, there are cheaper, more entry-level models such as T6 and SL1 (both of which happen to use the same image sensor and similar AF as the T3i, by the way).
Note the T6
i is near the top of the Rebel line... a more advanced model. The "STM" lens with the T6i are also is better performing than the unlabelled "micro motor" lenses often in kit with the more entry-level models.
She says she wants to photography landscapes, nature and people. Any camera can do those things. How well it does them will come down to what lens is used upon the camera, than the camera itself.
For example, a lot of the time wide angle lenses are wanted for landscapes... You can easily spend $900, $1000 or more on a wide angle zoom! Canon offers a <$300 EF-S 10-18mm IS STM that's quite good, while still being relatively compact and lightweight. It's a bit plasticky, but still a real bargain! (Nikon has just recently announced a similar budget priced ultrawide zoom, but it's not yet in stores and I haven't seen any reviews and tests done with it.)
"Nature" can mean a lot of things... Are we talking about wildlife where a telephoto such as a 55-250mm or 70-300mm would be wanted? Or are does she mean small subjects where a macro lens 60mm to 100mm or so would be the best choice? If she chooses a Canon camera, there are a number of options from around $300 to over $10,000! One lens I'd recommend she avoid is the Canon EF
75-300mm "III" (non IS, non USM). It's often offered cheap in bundles with various cameras, but isn't a particularly good zoom. The EF-S 55-250mm IS STM or EF 70-300mm IS USM are a bit more expensive, but still pretty affordable and are much, much better lenses. There are a number of different good macro lenses, if that's what interests your friend. I won't try to get into too much detail about them here.
For portraits of people, a short telephoto lens is usually what's wanted... wide angle lenses make for strong distortion and long telephotos require a lot of working space. For a low cost portrait lens, I'd recommend something like the Canon EF 50mm f/1.8 STM, which usually sells for around $120. Because they're also short telephotos, some people like to use a macro lens for dual purpose... for portraits of people, in addition to macro. One of the best for that type of use is the Tamron 60mm f/2.0. It has a stop larger aperture than most macro lenses, which can be useful for portraiture. But, it's more expensive at about $500.
I'm using Canon examples above because that's the system I use and know best. To be fair, you can set up a similar kit in most brands. However, tell your friend to be sure to look carefully at the system beyond the camera and kit lens that comes with it... Maybe not to purchase now, but to add sometime in the future.