If you look at the output of fw ctl conntab, you have your answer:
<(outbound, src=[10.6.5.251,44738], dest=[3.234.44.184,443], TCP); 2503/3600, rule=0, tcp state=DST_FIN, service=nfsd(393), Ifnsin=1, Ifnsout=1, conn modules: Authentication, FG-1, ISP-Redundancy, SynDoSDefender>
This connection is related to https (TCP 443, as bolded in the above output).
If you just want to see the number of https connections from a specific IP, from expert mode:
fw ctl conntab | grep x.y.z.w | grep ",443], TCP" | wc -l