Fiber Optics Connector Cleaner is to clean end surface of connector ferrule from dirt so as to enable smooth light transmission from one connector to the other with lowest possible losses.
Alternatively you can use isoprophyl alcohol and normal cotton facial tissue that is available in any pharmacy stores to clean the end surface of fiber optics connector ferrule.
Always check end ferrule surface after cleaning either by using 100x or 400x microscope.
A good end ferrule surface (the most left photo) will provide a smooth laser transmitted from one connector to the other connector.
Otherwise you may need to repeat the cleaning process or perhaps you need to re-splice or re-terminate with new connector.
I have been in the field of fiber optics since early 1990s. I gained fiber optics skills and knowledge via my working experience as end-user, main contractor and sub-contractor and finally as an optical fiber enterpreneur.