Need help understanding wheel sizes
Having a look at the link provided in the comments the wheel make and model is pretty clear. Following a swift Google search the same wheel is advertised on Amazon as a 26".

https://www.amazon.co.uk/Hybrid-Front-Wheel-Knives-Dx3000/dp/6254401010

So, any 26" tyre  should fit you fine, although I'd be questionable of the seller, as mentioned in the comments above.