Questions & Answers about Oczywiście, że możesz tu spać.
Why is the word że (that) used here? English doesn't say "Of course that you can".
In Polish, when oczywiście (of course) introduces a new thought with its own conjugated verb (like możesz), it is very common to connect them with że. You can actually drop it and say Oczywiście możesz tu spać, but adding że makes it sound very natural and conversational.
Why is there a comma before że?
Polish punctuation rules are strict about this: you must almost always place a comma before the word że (that). This is a big difference from English, which rarely uses commas before "that".
Why is spać in its infinitive (dictionary) form instead of being conjugated?
Because it directly follows the verb możesz (you can). Just like in English, when you use a modal verb (words expressing ability, permission, or necessity), the main verb that comes after it stays in its basic infinitive form.
What is the difference between tu and tutaj? Could I use tutaj in this sentence?
Yes, you could absolutely say Oczywiście, że możesz tutaj spać. Both tu and tutaj mean "here" and are completely interchangeable. The word tu is simply a shorter version that is very popular in everyday speech.