"to be sulk for today" sounds quite strange, but the word 'sulk' is like 'refunfuñar'. It's what happens when someone is upset and then they passive-aggressively go quiet and refuse to talk / participate in an activity.

Well "sulking" means being in a bad mood, like being depressed about something, but I don't think that sentence really makes sense to be honest

Hey Wilson I believe some more context is needed for that phrase since it doesn’t make much sense! “Sulking” is being annoyed at something and not want to discuss it. Other than that I’m not sure what else I could get from that 😂

It means to be angry about something and refuse to talk about it.