the placeholder text gives an example. the common practice is to separate with a colon :. so if your ip is 5.5.5.5 and your port is 5000, you'd write it as 5.5.5.5:5000
cln uses "runes" which differ from lnd's "macaroons" but they both do the same thing: grant permissions to the bearer (in this case, SN). The certificate is for encrypting communication with anything that talks to your node (in this case, SN). It's like the s in https.
:. so if your ip is5.5.5.5and your port is5000, you'd write it as5.5.5.5:5000sinhttps.