Final answer:
The woman applied henna on her nails for coloring, which is a natural dye used in various cultures for body art, especially during special events.
Step-by-step explanation:
The woman applied henna on her nails by dipping her fingertips in it, which is a traditional body art process. Henna, derived from the henna plant's leaves, is known for staining the skin and nails with a red or orange color, which reflects the cultural, familial, and religious affiliations during celebratory occasions like weddings and festivals. Unlike nail polish, which is a cosmetic product applied for coloring nails, henna is a natural dye that creates a temporary stain. Custom-blended essential oils and makeup designs do not serve the purpose of coloring nails.