Learn Russian: В понедельник нам всегда скучно.

This sentence uses an impersonal expression to describe a state or feeling, which is the focus of your current lesson. Instead of saying 'We are bored,' Russian literally says 'To us it is boring.' The person experiencing the feeling is put in the Dative case (нам), and the feeling itself is described with the adverb скучно.

How is the чн in скучно pronounced?

Even though it is spelled with чн, it is pronounced like шн (shn), making the word sound like 'skoosh-na'. This is a special pronunciation rule for a few common Russian words, which you might remember from the word конечно (of course).

Is в понедельник in the Prepositional case?

No, it is actually in the Accusative case! To say 'on' a certain day of the week, Russian uses the preposition в followed by the Accusative case. Because понедельник is a masculine inanimate noun, its Accusative form looks exactly the same as its dictionary form.

Can I change the word order and say Нам всегда скучно в понедельник?

Yes, absolutely. Russian word order is very flexible. Putting the time phrase в понедельник at the beginning simply sets the scene first ('As for Monday...'), which is a very natural way to speak. Putting it at the end is also completely correct and sounds like a neutral statement of fact.