What does it mean when a girls calls you out of nowhere?

Answer 1

She's probably bored and finds you interesting. Or she's interested in you, but don't take it as too strong a hint, it may be nothing.

Answer 2

When a girl calls you out of nowhere, it could mean that she has something important to tell you, wants to catch up, or simply enjoys talking to you. It may show that she values your connection and wants to engage with you.