U6 (Uranus), S9 (September), I4 (Iota), C11 (Corinthians), S6 (Sugar)
These are related items in order. The letter refers to the initial letter of each item. The number refers to the number of letters in each word.
For example,
V5, E5, M4, J7, S6 are some of the planets in our solar system – VENUS, EARTH, MARS, JUPITER, SATURN
A5, M3, J4, J4, A6 are the months APRIL to AUGUST
D5, E7, Z4, E3, T5 are letters of the Greek Alphabet DELTA to THETA
M4, L4, J4, A4, R6 are books of the New Testament from MARK to ROMANS
P5, C6, L7, F5, W4 are Wedding Anniversaries from PAPER to WOOD