A transceiver is a transmitter and receiver sharing one box, one frequency control and one antenna. An HF transceiver covers the shortwave bands, usually 160 m through 10 m, often 6 m too, and is the usual heart of a home station. It is the radio you use to work other continents.
How it fits the station
The usual connections around an HF rig. Most are optional except power, antenna and a way to key or talk.
Inside, one set of circuits is shared between receive and transmit, and the push-to-talk line decides which path is live:
One box, two paths. The PTT input decides which one is live.
Crowded bands put many strong signals near the one you want. Dynamic range and selectivity decide whether you hear it cleanly; see Sensitivity, selectivity and dynamic range
Filters and DSP
Narrow CW and SSB filters, notch and noise reduction make weak signals readable; see Filters in radios
Built-in antenna tuner
Matches a modest mismatch so the rig sees a load it can drive. It cannot fix a poor antenna
Spectrum display
Shows activity around you at a glance, a feature of SDR transceivers and many hybrids