This type of wrench is used to hold and turn taps to create screw threads, and it can also be used with reamers and screw extractors. The wrench in the image appears to be a Beta 436/1 model, which is similar in design to the Facom 830A series.
T-handle tap wrenches are ideal for use in tight spaces where a standard wrench would be difficult to operate.
The ratchet feature allows for right and left-hand operation, as well as a locked, non-ratchet position.
The chuck is adjustable to fit different sizes of taps.