Ok here is a really simple answer, but I suggest you search poketracker threads on here for a more detailed explanation.
19/10/2 474 relates to stats that are usually available for tracking databases. the 1st number is the VPIP - which means the % of time you voluntarily put money into a pot (excl the blinds), so the higher the %age the more pots you play.
The second number the the PF - which means the %age of times you raise the pot pre flop.
The 3rd number the AF - which is your total aggression factor.
Last number is the total amount of hands you have those stats for.
These are stats from programs like PokerTracker and the typical format will be
VP$IP- voluntarily put $ in the pot here it suggests this particular opponent sees flops 19% of the time. A bit misleading as checking a big blind walk does not count. Completing the small blind does.
PFR - preflop raise %- how often does this opponent raise preflop
AF - Aggression Factor- still looking for a great definition of this
Hands tracked -
If the first number is the amount of time they voluntarily put money in the pot preflop and the second number is the amount of times they raise preflop. Does it then follow that someone who is 20/10 raises half the time and limps the other half they VPIP or raises 10% of the time they VPIP?