To understand what a region proposal is, let's break the term into its constituents—region and proposal.
A region is a portion of the total image where the pixels in that portion have very similar values.
A region proposal is the smaller portion of the total image, where there is a higher chance of the portion belonging to a particular object.
A region proposal is useful, as we generate candidates from the image where the chances of an object being located in one of those regions is high. This comes in handy in the object localization tasks, where we need to have a bounding box around the object that is similar to what we have in the picture in the previous section.
