2 meter is a Ham radio (amateur radio) frequency band around 144.000-148.000 Mhz. 2 meter is the length of the waveform of this AC signal. this is also called VHF (very High Frequency)
CB is 27.195 Mhz (channel 19) which is an 11 meter waveform, this is called HF (high frequency).
2M is a service you need to be licensed for, but its only requires a simple test that is mostly about the rules.
Actually 2m is a "line of sight" signal that does not bend very much as it goes out through the air. 2M will pass through the atmosphere into space.
11m can bend around the curve of the earth some. in mountain areas you used to see the local police would still use HF radios because in some places they it just worked better. 11m mostly reflects off the atmosphere and "skips" back to the ground (depending on atmosphere conditions) that is why CB is so noisy, where sometimes its even unusable.
But where 2 meters shines is there is amateur radio clubs that put "repeaters" on top of mountains.
Your radio receives freqency A, and transmitters on frequency B.
The repeater receives this signal B and re transmits the signal (at same time it receives it) on frequency A.
Everybody's radio has both frequencies programed, and everybody is listening to frequency A.
the advantages of this is your mobile can transmit maybe 50 miles or more to the repeater, which re transmits the frequency the same distance or more, thus you can reach over 100 miles using repeaters. Sometimes these repeaters also have the ability to connect to a phone, or even the internet to attach to another repeater anywhere in the world.
The problem is there may not be many amateur radio operators listening to the repeaters.