It's difficult to say with any definitiveness... spots can have many causes. But in the absence of any insect activity and not knowing what the underside or the rest of the plant looks like, it would suggest some kind of blight or perhaps a rust. These are air or soil borne organisms that are difficult to control after they have taken ahold. I suggest you contact a local extension service in your area or a garden club or master gardeners association. Someone can take a look at the whole plant and the cultural conditions for a better diagnosis.

If the other camellias are not affected you should separate the affected plant immediately: perhaps put it outdoors on a shady porch if the others are indoors etc. Watch the others very closely and remove them at the first sign of trouble.

Thank You so much.I think it could be rust because we sprinkled with copper against blight.

That's excellent that you were spraying the plants with a copper spray as a preventative, but that's not what causes a "rust" on plants. Rust is a name for a variety of fungus infections that can affect many kinds of plants.  I guess folks have called them "rusts" because they're often reddish or brown, like the other kind of rust. Sorry to be confusing.

We sprayed with copper only after these spots had appeared so I assume it could be the other one disease.(just for not misunderstand me....)What is suggested to use to get rid of rust fungus?

Rust, like the other blights etc. can't be "cured"; next season start spraying the fungicide in anticipation of the possible infection in order to prevent its repeat. The spraying after the spots appeared is good to help prevent its spread to the other plants, but won't help this one. Good news is that in most cases these are not fatal to the plants. Be sure to clean up all the leaves and other debris that fall from the plants and dispose of it in the garbage. If they are in pots, keep them well away from each other. They'll be fine.

Many thanks!

You're very welcome!