I'm new to lipos and have a vehicle that is 2s lipo battery and 3s lipo capable. What I'm wondering is what is the difference between the 2? Does one make the vehicle faster or run longer? Also what does the "mah" on a battery stand for and what is it effect to a battery? Thanks in advance for any help.

From what i know (and im a beginner), a 3s lipo should put out more power than the 2s. And "mah" stands for "milliamp hour" referring to the capacity of the battery. More the mah->bigger the battery->longer run times.
Please correct me if im wrong.

P.S. Google is your friend, you should find all your answers there.

hey i hope this will help you understand about lipos better http://fpvcrazy.net/2016/09/06/lipos-charger/

The 's' in 2s or 3s stands for cell. Each cell carries a voltage from 3-4.2V (below 3V will damage the cell). Hence a 3S lipo has a voltage of 9 to 12.6V and a 2S lipo has a voltage of 6 to 8.4V.

mAh is the capacity of the lipo, ergo how long it will last.

A vehicle would run faster when a high voltage is provided to it, so a 3s would be faster than a 2s for the same setup.