The transformer is used to transform a medium voltage supply to a low voltage supply, e.g. from 11 000 V to 400 V. A transformer is rated in kVA, kilo-Volt-Amps, which is a measurement of electrical power.
RF is radio frequency. IF is intermediate frequency used inside the TV for processing. AF is audio frequency. SAP is second audio program which may have another language or other soundtrack as an option to the main soundtrack.