So that is a 10ml vial of 300mg/ml test.
So it contains 3000mgs of test. (10ml x 300mg/ml = 3000mg)
If you were to do 500mg of test per week it would last you 6 weeks. (3000mg / (500mg/week) = 6 weeks)

Smaller containers are called ampules (amps). They are only 1ml.