SFTP: Shielded Foiled Twisted Pair: If you have possible sources of interference along the installation route, such as other cables, electricity (220V) for example. The metal braid reduces possible sources of interference such as electromagnetic fields, e.g. along power cables.
UFTP: Unshielded Foiled Twisted Pair: If you have no sources of interference.

The shielded refers to a metal wire braided sleeve that you have under the insulation layer and around the wire pairs (which are wrapped in a kind of aluminium foil per pair) of the cable and which end on the metal shoes of the plugs - and these are earthed via the device (and Unshielded does not have this).
I use S/FTP wherever possible, regardless of whether there is currently power nearby or not.
What SFTP cannot do or is not well shielded are installation locations with large electrical machines with high voltage or current higher than 220V. You would have to choose a different installation route...
Hope it helps. LG

Exactly. I would always use S/FTP.