RoHS (Restriction of Hazardous Substances Directive) covers a number of hazardous substances, not just lead. Google RoHS for a list.
You can not sell an electronic product in Europe if it contains any of the listed toxins. It seems likely that other parts of the world will follow suit.
The main challenge with RoHS is that you can not use solder that contains lead. Lead-free solder has a higher melting point and is generally a bit more tricky to work with.
On the bright side, you are less likely to cause lead poisoning to yourself or anyone else manufacturing or recycling your product :-)
EDIT: The general idea is that these toxins tend to concentrate in places like landfills. Sooner or later this stuff returns to bite you through fires, leaks etc.
The RoHS directive is not an absolute ban, it specifies the max concentration. You can for example have 0.1% lead in your product. Industrial products may not require RoHS compliance, you can for example use NiCd batteries in medical equipment even if it is banned for consumer use. But the batteries have to be brought in to recycling stations after use.
As an individual you are welcome to lick lead all day long or to import non-compliant products for your own use. You can use solder containing lead as long as you don't sell what you make.