Peace, this beautiful bird is a Budgerigar, and in some Arab countries it is known as the "lovebird" or "perruche".
As for determining its age accurately from the picture, here is:
Its species and sex
Species: Australian Budgerigar (Dutch mutation/recessive or dominant spotted due to white color and variation in the stripes).
Sex: Male, which is evident from the color of the "cere" (the fleshy area above the beak surrounding the nostrils), which appears light blue/bluish.
Age estimation
This bird is considered young (juvenile), not a very small chick, and not an old bird. Its approximate age ranges between 4 to 8 months.
And the evidence for that from the picture is:
Pupil: Its eyes appear completely black, or the white pupil has started to appear very lightly (fully adult birds have a clear white ring around their eyes).
Forehead: The forehead is white and completely free of black stripes (a young chick has black stripes reaching its beak, and they disappear after the first molt at 3 to 4 months of age).
Nasal cere: It has started to take on the clear, stable blue color characteristic of adult males.
💡 Quick fact: The average lifespan of budgies, if they receive excellent care and a balanced diet, ranges from 5 to 8 years, and sometimes they can live up to 10 years!
And peace, mercy, and blessings of God be upon you.