Certain traffic lights have a button to signal that you (the pedestrian) wants to cross. Those traffic lights are usually optimized for cars, as they know the no pedestrians will usually cross.

The blonde keeps pressing the button, repeatedly, which have no effect. When asked about it, she says its to call her friend (like a comms system in an apartment building).

The other person, which is also blonde, fails to realise the mix up (traffic lights vs apartment building) and instead says that the friend must be home, "because the lights are on" - which, in an apartment would suggest someone being home.