Well Alex, LiPo means Lithium Polymer. That's the materials the pack is made of. Somewhere on the pack it should have some numbers. There should be a voltage rating, ie. 7.4, 11.1, 14.8, etc. There should be a milliamp capacity, such as 1100mah, 1500mah, etc. Then there should be a discharge rate, such as 10C, 20C, etc.
Voltage= how many cells there are, unless some cells are parallel. that's what the 2s, 3s, 3s1p, etc. stands for. 2s= 2cells, 3s=3 cells, 3s1p stands for 3cells in series, 1 parallel. EachLiPo cell is 3.7 volts, so 1s= 3.7v, 2s= 7.4v, 3s= 11.1v,etc. When cells or packs are run parallel, the voltage stays the same. When packs are run in series, thevoltage increases by the number of cells added.With me so far??
Nextis capacity. The milliamprating ishow much capacity the battery can hold.The higher this number is, the more capacity the battery has.
Then there's the discharge rate, 10C, 20C, etc. This is the rate that the pack can safely discharge it's capacity without excessive heat or damage to the pack.
All of this needs to be taken into consideration when deciding what motor you run, prop size, weight of model, type of flying, etc.
Hope this helps.