That depends on three main factors:
☛ The breed of chicken. Some chickens are bred for meat production and lay few eggs; some are bred for egg production and can lay as often as once a day; some are bred as "dual purpose" andare good for both egg-laying and meat, although not optimal for either.
☛ The hen's age. Hens start to lay at 4-5 months of age, and lay best during their first year. Each year after that their production decreases.
☛ The season. In the winter (with fewer daylight hours), egg production drastically decreases. High laying season is summer.
A healthy, young hen bred for egg-laying can lay almost an egg a day!