depends on how many chromosomes and genes are present in the plant. the greater the number the more combinations there are. 2 chromosomes each = 4 combinations 4 chromosomes = 16 combinations. but there are 100's of genes too.
and are you are self crossing it or crossing it with siblings. that causes another raft of combinations. They will still be essentially the same species but what is the norm? Think about all the variations in the human species!
but the short answer is they will be unpredictable for some time.

The answer is that a seed planted from a hybrid plant would probably give you a plant that will resemble the original, i.e., revert back to it's original type. For example, a seed planted from a hybrid rose would more than likely give you a wild (dog rose). And an apple pip planted from a hybrid apple would in all probability give you a crab apple. Having said that, nature has a way of changing things and sometimes causes mutations which give us the wonderful diversity in nature that we now have.

in 1868 Maria Ann Smith planted an apple pip and it grew into a tree which bore lovely, different apples... The Granny Smith was born.

At one time all humans had brown eyes. Due to a genetic mutation gene in our chromosomes thousands of years ago this created an ability to produce blue eyes, etc.

The only sure way that a plant can be propagated that will resemble the parent or donor plant is by division or cuttings. In fact the offspring would be an exact copy as it would share the exact same DNA as the mother plant.

and even clones can vary depending on the environmental factors. Taller if in the shade for example.

OK, thanks everyone I get it.

So when you have packet of Hybrid seeds for tomatoes, peppers Etc. how are they (in quantities of 100s of 1000s) mass produced?

Obviously not from division or cuttings? so putting it another way are the parent plants "special" and kept in high security? or are these parent plants reproducable?

Creating a hybrid is a complicated process and can take many years to get the desired result. They are mainly created by cross pollination and maybe further cross pollination to get a distinctly different plant and then any offspring's from this end result is called an F1 hybrid.

Taking seeds from these 'special' plants as you put it are then sold off as new hybrids. Growing the seeds from these new hybrid plants and then further crossing two F1 hybrids produces an F2 plant, etc, etc. All quite complicated but never the less interesting.

If you a interested in learning about plant hybridization, then my advice would be to Google the subject and read up on it as it would take a lot of time to explain it.