This is a small refractor telescope fitted into an equatorial mount to assist in polar alignment. The polarscope is aligned along the polar axis of the telescope and contains crosshairs and constellation / star markings for centring on either the northern or southern celestial pole.
Accurate polar alignment is essential to take good quality, long-exposure images, in which the star field needs to be tracked. It's easier to achieve in the Northern Hemisphere where bright star Polaris can be used as a marker.