It means what it says, but it is a simplification.
Using the Channel Master series as another example for comparison of specs:
3410
A one port distribution amp does not contain a splitter, so its gain is 15 dB.
http://www.channelmaster.com/Antenna..._p/cm-3410.htm
3412
A 2-port distribution amp contains an amp with a gain of 15 dB and a 2-way splitter with a loss of 3.5 dB per port, for a NET gain of 11.5 dB per port.
http://www.channelmaster.com/Antenna..._p/cm-3412.htm
3414
A 4-port distribution amp contains an amp with a gain of 15 dB and a 4-way splitter with a loss of 7 dB per port, for a NET gain of 8 dB per port.
http://www.channelmaster.com/Antenna..._p/cm-3414.htm
Just to male it even more confusing, PCT International not only makes the CM distribution amps with the stupid hard-to-read black labels, they also make the mini drop passive return CATV amps with white labels that are equivalent.
http://www.pctstore.com/RF_Amplifier...fiers_s/58.htm