Translation:The plate is between the glass and the bowl.
Because "Schüssel" (= "bowl") is a feminine noun. Thus, as in this sentence the preposition "zwischen" requires the dative form of the words that follow it, "die Schüssel" turns into "der Schüssel", where "der" is the Dativ of "die".
Should have a look on this link below. It's likely to clarify this issue much better than I can do:
I'm confused (again); I also type up my lessons, and I was looking for the plural of "Schüssel." I found this site: https://www.verbformen.com/declension/nouns/?w=Sch%C3%BCssel and I noticed that it shows "die" instead of "der" on the nominative & accusative forms. Half the time, I don't know the difference between them - is there ANY easy way to remember what form you're looking at?
Are you getting 'die Schüssel' and 'der Schlülussel' confused? If you are, they are 2 different words: bowl (feminine) and key (masculine) . As for nominative and accusative, you just need to figure out which is the subject of the sentence and which is the object. The verb takes the object as an argument, and the subject is what is doing the action.