The END function block marks the end of a flow.
If the flow reaches this function block it stops and cannot leave it by itself. Only a reset signal to the according START function block or a restart of the application enables a new processing of the flow. Other flows are not affected by a stopped flow and works as usual.
The END function block is active if the flow reaches this block. It stays in this state until the whole flow is reset.
To understand the Flow Chart blocks better, you can have a look at our example Right use of Flow Chart blocks...
If the function block is active, the symbol will be colored green in the online mode.