blob stands for binary large object and represents the file content in binary data.
Because in a computer, all data are binary data, this name is used logically to represent any file content where the mime (type) is unknown.
All files are blob and this is the role of a third application to retrieve the binary content and then decode/encode it in the target mime (type).
For instance, if this is text data, a text editor would retrieve the binary content and would decode it into text.
If a file system indicates that it's a blob storage system, it indicates then that it may store any type of content (ie any mime)
Most file system does: