9/8 is a very fun and challenging time signature. The 9/8 indicates 9 eighth notes per measure. A quarter note is still equal to 2 eighth notes, and there are no tuplets, so 3 eighths are indeed three eighths. What I’ve found is that any time signature with an 8 at the bottom almost always means the tune has a triplet feel, so 6/8 feels like the triplet version of 2/4 and, with that line of thinking, 9/8 feels like the triplet version of 3/4.