TCP session?

Im monitoring router traffic on my home network through the Linksys
firewall. I see lots of TCP "Outs" (in green) permitted from one of the PCs
on the network but no "INs". Does this mean that the "Out" really
represents an exchange of data through that port or both input and output
data as long as the session is valid?

I also see lots of Red "Ins" that are blocked and show Cable Modem IP vs PC
IP so I assume those hit the fireware and were rejected becuase there was
not an associated request first to open a session?.

Is that even close?

thanks for any insight
Im using Wall Watcher to montor router firewall data.

thx