When you say the bearing is turning, can I assume you mean the gear is turning?
When the extruder does its thing, the motor turns the small gear, the small gear turns the big gear, the big gear turns the hobbed bolt, the hobbed bolt has teeth that grab the filament and push the filament down towards the nozzle, the nozzle has a resistor that heats everything, the heat causes the filament melt, and finally the pressure from the pushed filament causes the molten plastic to extrude out the nozzle.
If the gears are turning but the filament isn’t extruding then you have a few possible problems:
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The temperature isn’t hot enough. If the temperature isn’t hot enough, it won’t be able to melt the filament quickly enough to extrude out the nozzle causing the hobbed bolt to grind away at the filament.
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The hobbed bolt isn’t able to grab the filament any more. If so maybe you need to tighten the thumb bolts to get it to dig into the filament more. Make sure you verify the temperature is ok for the type of filament you want to use first.
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Extrusion speed. This is only a guess, but I would imagine if the extrusion speed is too high it could have a hard time extruding fast enough.
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Partial obstruction in the nozzle. This is only a guess, but if there was something blocking the filament, it could also have a hard time extruding the filament fast enough to get out of the way.
Disclaimer: I’ve only been doing this for a little more than a month, so I could be missing something obvious here or saying crazy things to embarrass myself