sRGB is a standard RGB color space. (What is a color space?)
At the moment, sRGB is the only appropriate color space for images uploaded to the web, because most browsers, applications, and devices are designed to work with sRGB, and assume that images are in the sRGB color space. In fact, most browser simply ignore the embedded color space information in images and render them as sRGB images. So if your uploaded images are converted to sRGB it is very likely that colors will appear as you intended.