What does this symbol represent? It is connected to a contactor.
The symbol represents a triac, of which the gates of the thyristors are drawn weird. (see other remarks).
It is part of a softstarter, a the softstarter also contains electronics for controlling the gate(s) of the triac(s).
The symbol represents a soft starter, which is used for smooth starting and stopping of the motor.
Here it shows 2 SCR devices connected in inverse parallel connection.