It's a battery protection and cell balance board. It should disconnect the battery from the external wiring if any cell gets over-discharged or over-voltage. The balance network should equalise voltage and allow charging to continue if one cell reaches maximum voltage before the others.
In summary, it should prevent the cells being wrecked by over-discharge or exploding due to overcharge.
It is not a charger or charge control board, that is a totally separate function. The charge controller needs to regulate the voltage to the battery pack to 4.20V per cell, plus have a current limit so the pack does not get excess current when the cell voltage is low.
See the circuit below as an example.
I've used similar battery protection/balance boards, they seem OK. Just avoid ones that do not include both functions.
ps. Lithium packs are commonly rated at mid-charge voltage, like other rechargeables - based on 3.6 - 3.7V per cell for lithium types. That's where the 14.8V comes from.
The power switch FETs appear to be between B- and P- on your board.
This is a simple charger circuit I designed for use with a battery pack built like that; it's made to also bypass the battery pack and run the load directly when external power is available, so the charging is not affected be load.