Crock pot on power inverter
The purpose of the inverter is to make "home-made" AC power from your battery's DC power, so you can power normal home appliances.

So, yes, you can use that slow cooker using the output of the inverter.  However, on high power, the cooker will draw about 2 Amp at 120 V, and the inverter will draw about 20 Amp from your 12 V battery to produce that.  Your 105 Ah battery would be very dead in 4 hours or so.