Við tilkynnum þér niðurstöðuna á morgun.

we

Breakdown of Við tilkynnum þér niðurstöðuna á morgun.

• á morgun: tomorrow
• þér: you (polite)
• niðurstaðan: the result

Questions & Answers about Við tilkynnum þér niðurstöðuna á morgun.

Why is the verb tilkynnum ending in -um?

Tilkynnum is the 1st person plural present tense form of the verb tilkynna (to announce/notify).
In Icelandic, present tense endings change with the subject:

• ég tilkynni (I announce)
• þú tilkynnir (you announce)
• við tilkynnum (we announce)
• þið tilkynnið (you plural announce)
• þeir/þær/þau tilkynna (they announce)

So -um matches við (we).

If it says “tomorrow,” why is the verb in the present tense and not a future tense?

Icelandic commonly uses the present tense for scheduled/expected future actions, especially with a clear time phrase like á morgun (tomorrow).
You can also use a more explicit future construction, e.g.:

• Við munum tilkynna þér niðurstöðuna á morgun. (We will notify you tomorrow.) But the plain present tilkynnum is very normal here.

Why is it þér and not þú/þig?