Why For satellites, "mode" is shorthand for which band you transmit on (uplink) and which band you listen on (downlink), not anything about the orbit. The modern notation uses a letter for each band in uplink/downlink order: H (21 MHz), A (29 MHz), V (145 MHz), U (435 MHz), L (1.2 GHz), S (2.4 GHz). So a Mode U/V satellite hears you on 70 cm and sends the transponder output down on 2 meters. Older single-letter designations like Mode B and Mode J meant the same kind of band pairing.
Watch out The orbit-related choices describe the satellite's orbital parameters, which matter for pass prediction and Doppler but are described by terms like LEO, geostationary, polar or equatorial, not by "mode"; satellite orientation is called attitude or spin stabilization.
Mode = two bands, uplink first: U/V means up on 70 cm, down on 2 m. V=145, U=435, L=1.2G, S=2.4G.