2 hours after eating and 1 hour excercise my blood sugar is 5.1 mmol is this good?

5.1 mmol/l (millimoles per litre) [that's 92 mg/dL (milligrams per deciLiter) for our American cousins] 2 hours after eating is absolutely 'normal', my friend. i.e. it IS good.

You have the ability to test your blood glucose level yet you don't have any means to know what is good.

Right.