2S BMS protection board means 2x3.7v = 7.4v battery pack bms. This BMS protection board is for 5A current limit. This board supports 18650 Model Lithium Ion battery Model.
This board give protection in Over charge and Low discharge, Proper Charging.
Remember 5A cuurent does not mean 5AH. 5A means for max 40 watts motor. You can make the battery pack even 100AH but the output power shuld be limited to 40 watts max if you want to use this bms baord.