It indicates the car speed.
See also:
If an interior light burns out
Modifications or repairs to the electrical system carried out incorrectly
and without bearing the features of the system in mind can cause malfunctions with
the risk of fire.
See “If a bulb burn ...
Fiat 500 Owners Manual
h1 {color: red;}
h2 {color: green;}
h3 {color: blue;}
h4 {color: #FF00FF;}
...
Seat Belt Extender
If a seat belt is too short, even when fully extended, and when the adjustable
upper shoulder belt anchorage (if equipped) is in its lowest position, your authorized
dealer can provide you with a ...