The amplitude from the graph (highest point it reaches) is about 10.5 Jupiter Diameters. One Jupiter Diameter is around 140,000 km, and 1 AU is about 150,000,000 km so 1 JD = 0.0009 AU, and 10.5 JD = 0.001 AU (approximately).
The period is the gap between "peaks", how long it takes for the graph to reach the same point again. This happens on day 1-2 and day 18-19, so the period is approximately 17 days = 17/365 = 0.0466 years.
M (in solar masses) is given by a^3 / P^2 = 0.001^3 / 0.0466^2 = 0.00043 solar masses.