Hola soy nuevo en esto y me rechazaron casi todas las imágenes

DSC_0518.JPG - not sharply focused and blown higlights

DSC_0071.JPG - depth of field is too shallow, blown highlights, messy background

DSC_0434.JPG - blurry, underexposed

DSC_0447.JPG - artifacts, completely blown out clouds, white balance problem, poor focus

DSC_0481.JPG - poorly composed and lit; unattractive plate of food

Adobe Stock is not looking for quick snapshots; they are looking for well lit, well exposed and nicely composed images taken with planning and thoughtfulness. The links that Abambo provided should help you to understand the quality level that is desired.

If you are new to stock, you should consider these resources: https://helpx.adobe.com/stock/contributor/tutorials.html
Please read the contributor user manual for more information on Adobe stock contributions: https://helpx.adobe.com/stock/contributor/user-guide.html
See here for rejection reasons: https://helpx.adobe.com/stock/contributor/help/reasons-for-content-rejection.html
and especially quality and technical issues: https://helpx.adobe.com/stock/contributor/help/quality-and-technical-issues.html

@Ricky336 summed it up pretty well.  Focus and depth of field, white balance and saturation, exposure, and composition are your main problems. Also some of your photos have a little noise.

The landscape photo is out of focus, very blue, is over saturated, has blown out highlights (the clouds), and has several objects at the bottom which should be removed (shadows and umbrellas).