Learn Turkish: Bugün çok özel bir gün. - Today is a very special day.

In Turkish, the word bir (a/an) usually goes right before the noun it belongs to, after any adjectives. So 'a very special day' is phrased as 'very special a day' (çok özel bir gün).

Where is the word for 'is' in this sentence?

In everyday Turkish, the word for 'is' is often left out. You don't need to add a suffix like -dir here; just putting the subject (bugün) and the description (çok özel bir gün) next to each other is enough to mean 'Today is a very special day.'

Is bugün made up of two different words?

Yes! It literally combines bu (this) and gün (day). Over time, they merged into the single word bugün to mean 'today.'

Could I use için (for) with a sentence like this?

Yes! While this exact sentence doesn't have it, you can easily add için to say who the day is special for. For example, Benim için çok özel bir gün means 'It is a very special day for me.'