These are ordinary sewing needles suitable for sewing with regular sewing thread. Use them, for example, for hemming or repairing seams that have come undone.
Sizes 3/9 are a bit large and can also be used with slightly thicker sewing thread, such as for topstitching and buttonholes.
Sizes 5/10 are a bit smaller and well-suited for regular thin sewing thread in fabrics like cotton shirts and similar items.