Your phone and the Sun answer different questions.
Local Time helps a whole region agree. Solar Time describes the apparent Sun at one place. Because a time zone covers many longitudes and the apparent Sun does not move at a perfectly uniform clock rate through the year, the two readings usually differ.
Same noon, different numbers.
At the instant of local solar noon, SOLAR reads 12:00 Solar Time. Your civil clock might read 11:47, 12:36 or 13:54 depending on longitude, time-zone policy, daylight saving and date.
Why use a twenty-four-hour clock?
Solar Time preserves familiar hours and minutes. The difference is that the number is tied back to the apparent Sun, so 12:00 regains a direct astronomical meaning.
What SOLAR shows with it
A clock reading alone does not describe the experience of light. SOLAR pairs Solar Time with the current solar phase and the duration of day or night ahead.