This HOSA cable/adapter says it has a TRSF adapter. Is that a typo? What is TRSF?
It is not a typo.
TRS stands for tip, ring and sleeve. A TRS plug is the three-contact version of the TS plug (tip and sleeve).
F stands for female. Male and female plugs of the same type can connect to each other.
The 1/4" TRSF to dual 1/4" TS cable is used to convert a TRS cable to two TS cables.