Following the Frame, Step by Step

A broadcast frame sent from PC1 and received by SW1 would forward the frame over the trunk tagged as belonging to VLAN 10 to SW2. SW2 would see the tag, know it was a broadcast associated with VLAN 10, remove the tag, and forward the broadcast to all other interfaces associated with VLAN 10, including the switch port that is connected to PC2. These two core components (access ports being assigned to a single VLAN, and trunk ports that tag the traffic so that a receiving switch knows which VLAN a frame belongs to) are the core building blocks for Layer 2 switching, where a VLAN can extend beyond a single switch.