I thought, "The pronunciation of the German word Spaß and Спав are similar...?" Do not need to concern this :)
Yes, actually they are not similar in pronunciation at all. Since I don't have IPA symbols on my keyboard, to use an English approximation, German Spaß is pronounced like "shpass," while спав is pronounced like "spav."
The ß is more like a "ss" sound and the letter в is spoken with a "w" sound
Does it mean i was not sleeping or i did not sleep? (It accepted I did not sleep) i imagine i was not sleeping would be я не був спав or is it because of the ending of спав
It can be translated as either "was not sleeping" or "did not sleep". There is no continuous in Ukrainian.
Exercises "write it yourself" are important, but I wish I didn't look for Ukrainian keyboard on another website each time!
If you're using a smartphone, you can easily install a Ukrainian keyboard.
If you're using a browser, you can use the word bank instead of typing in (there's a switch button at the bottom).
Or if you really want to type without a given choice of words, you can also type using English transliteration. E.g. this exercise would be "ya ne spav". Unfortunately, it's unclear how Duolingo decides to convert Cyrillic letters to Latin ones. Other contributors in this course don't know, contributors from other Duolingo courses don't know :( The safest bet is BGN/PCGN, but it doesn't always work 100%. For example, if you use this online converter you will get "ya ne spav", but in this exercise it will tell you there is a typo. However, I have no idea where it thinks there's a typo :/