When a girl says "hi," the best reply would depend on the context and your relationship with the person. Here are some general and friendly responses you can consider:
- "Hi! How are you doing?"
- "Hey there! What's up?"
- "Hello! It's nice to hear from you."
- "Hi, [Her Name]! How's your day going?"
- "Hey! Long time no see. How have you been?"
- "Hi! What brings you here today?"
- "Hello! I hope you're having a great day."
These responses are polite and open-ended, which encourages further conversation. If you're close to the person or have an inside joke or shared experience, you can add a personal touch to your response. The key is to be friendly, approachable, and considerate of the other person's feelings.