My suspension has Pedal Lock Out and Low SPD. When would I want to have pedal lock out and what’s the advantage of the Low Spd settings?

I just upgraded from an entry level hardtail to a used carbon fiber XC bike I picked up for a steal. All the components are much nicer than what I had before. My goal now is to get fast on flowy trails. I’m not a gear head and mostly just want to have fun while exercising.