This camera appears to essentially be a phone camera placed into a body made to look like a compact 'point and shoot' or small advanced compact camera. Most of the "lens" is just window dressing for the tiny lens located in the middle. In some of the product photos there appears to be a flat, screw on "protective" filter in place to make the "lens" look much larger than it actually is.

The optional "lenses" are screw on adapters that attach in front of the actual lens permanently attached to the camera. They are similar to the add-on "telephoto", "wide angle", and "macro" attachments one can purchase to use on their phone's camera. Such "lenses" are also available to fit some lower cost SLR lenses, such as the 18-55mm kit lenses sold with many entry level DSLRs.

When the description says "fixed focus" what it probably means is that the focal length of the embedded lens on the camera has a fixed focal length. Several other clues in the description hint that the description is a less than perfect translation from another language.

The optional "lenses" will probably work about as well as similar attachments made for phone cameras do. I doubt you will have any control over being able to manually focus this camera. It will probably autofocus about like most phone cameras do. After all, what this camera appears to be is basically a phone camera disguised as a compact point and shoot or even a "bridge" camera.

The specific screw-on adapter lenses you would need for this camera have thread sizes of 52mm. They are made to screw onto 52mm threads such as those on the front of your camera. Since these types of adapters are made for use with larger "kit" lenses sold with entry level DSLRs, they might be slightly better quality than the sizes made to adapt to camera phones. Bu then again, they might not be.