Question regarding RFC7296 (IKEv2) PRF+

In RFC 7296, in section 2.13

What do the "K", "S", and T# represent?

And my follow-up question is, in section 2.14

What would be the K, S, and T# equivalent in

{SK_d | SK_ai | SK_ar | SK_ei | SK_er | SK_pi | SK_pr} = prf+ (SKEYSEED, Ni | Nr | SPIi | SPIr)

Thanks !