For someone very new to the whole idea of shooting with a flash, @
WayneF or anyone else with recommendations is this a good starter kit to learn with my D5300? Basically the only flash photography I have ever done was with an instamatic and flash cubes (remember those) and a little with the Minolta SLR, but my knowledge with it was to put the Vivitar flash on the hotshoe when I wanted to shoot indoors to no be underexposed using automatic flash settings (indoor snapshots and not often). I am looking to start playing with getting shots of flowers like @
dh photography, David gets with the black background. (I'm assuming he is using flash for this).
I have not seen the kit, but the VK750-II flash seems an extreme bargain for anyone that is price-conscious. It works well, it's affordable, and certainly it is a good starter flash. Even if you want more later after you're really into it, it can always be a great second flash (like for two umbrellas, etc). It does not have features like HSS or Commander compatibility, but neither does the D5300, so it's a good match.
You are aware that the radio triggers are for manual flash mode only? Which is nothing like automatic flash. Then the only thing responsible for setting the correct flash power to obtain correct flash exposure is You. Probably different at every new situation. That is not a bad thing, but manual flash is something to be learned. It's easy, if you want a brighter picture, just turn the flash power up and try again. Some prefer to use manual flash, but others cannot be bothered to learn it. Manual flash can work well for fixed subjects, where nothing moves, and you have time to adjust it, like portraits or macro. TTL automation works too, anywhere, and is good for following motion, like chasing kids (which is about impossible for manual flash).
The flash itself (on the camera hot shoe) can do automatic TTL mode, and TTL automation is point&shoot flash, often about right, but we still need to learn a bit (called Flash Compensation) to sometimes tweak it in. TTL just starts very close to correct, where manual flash does not, if still without experience. Typically any necessary tweaks are judged by how the first image looks on the camera rear LCD, then we can adjust the flash up or down (power level on manual flash, Flash Compensation on TTL flash). With any flash, it's common to sometimes need another try or two to get best result. True of both Manual and TTL modes, and of any flash model or brand.
Flash is a lot of fun for its own sake, and can make dramatic improvements, but you said new to flash, and I'm just trying to help attitude about first try.

Flash is pretty easy, but it does require our full attention. The only real concern is that not everyone is willing to give it Any attention.
The cables are used to trigger the camera shutter when used as a remote shutter. Nikon models uses about three different cables, and apparently two choices are provided in the kit. I have not seen these triggers, but typically this option is either camera shutter or remote flash, but not both at the same time. The remote flash function itself uses no cables.
The YN-560 flash is manual flash only, no TTL.
The VK750 II is both manual or TTL.
Manual is good, but any beginner will want to have TTL automation available. The camera can meter TTL, and we might as well get all the camera can do.