Could someone explain this construct?
Apparently it means "see you" and the phrase "vi ses i norge" means "see you in Norway" but I thought "vi" was the pronoun for "we".
Adding to what matfran said, "å sees" belongs to an odd group of verbs in Norwegian called s-verbs, and furthermore to a subgroup of these which function as reciprocal verbs.
Reciprocal verbs can never take a single singular subject, there will always be either a plural subject, or two or more singular subjects. These subjects are then doing the verb action to each other. All reciprocal verbs have this implicit "each other".
If you say "Jeg sees" (singular subject), you're not using the reciprocal verb "å sees", but rather the passive form of the regular verb "å se", and the meaning would be "I'm (being) seen".
Two of "å sees" reciprocal s-verb friends, "å møtes" and "å treffes" are easier to relate to English, as they can be used in the same way there. "We meet each other weekly" can be phrased as "We meet weekly" without anyone blinking an eye.
I think it is similar to "vemos" or "nos vemos" in Spanish (they use that expression in some areas in some Spanish speaking countries), that, literally is "we see" or "we see each other", but it means something like "see you soon", "we will see each other again soon", "until next time", "until later"....depending a little on the situation.