My dentist said i have soft teeth. what does this mean exactly?

One factor in decay: There is a genetic factor in tooth decay. But if you have a good healthy habit that is low in sugars , brush and floss, and have regular dental care you will be able to keep you teeth healthy.

Decay prone: Basically your dentist is telling you that your teeth are prone to decay. You have to be pro-active in your maintenance. Possibly have your teeth professionally cleaned 4 or more times per year, use an electric toothbrush, consider Fluoride treatments and home Fluoride usage. Consider dental sealants for unrestored back teeth.

'soft teeth" ?: I have heard this expression. It refers to people getting cavities more easily than others. Personally, I do not agree with this statement. There are cases of congenital problems with malformed enamel, but honestly they are few and far between. I think the term "soft teeth" is over\misused. With proper oral hygiene (brushing and flossing) and a proper diet, you should not get cavities.