Ports all have to do with the sleeve (mostly).. A port is just a hole in the sleeve, which makes the engine run. When the piston goes up and down it closes some ports and opens other which allows things (air/fuel) to come and go. In theory the more pots the more power but in some cases this is not true. A nice 5 port engine can beat some 7 port engines.

This is just a little info.. I am sure some one will go in to much more detail