Question

What is the equivalent of film speed on a digital camera

Answer 1

Digital cameras have far surpassed film in terms of sensitivity to light, with ISO equivalent speeds of up to 409,600

Answer 2

Digital and film cameras use the same standard, namely ISO standard since 1974.
Film speed using ASA have the same significance as today's ISO, unless the film is very old.
See more at:
https://en.wikipedia.org/wiki/Film_speed#ASA