This is a tank landing craft, capable of landing up to 5 medium tanks on an unprepared shore.
USSR had no landing craft to speak of before war. A few leftovers from WW1 Imperial Russia times were in a bad condition and not really capable of landing anything useful. So, when war situation required naval landings, anything was used, up to a cruiser docking in an enemy-held harbor and unloading infantry while firing the guns point-blank at the German defenders. That's why some of US built LCT mk.6 were aquired via lend-lease program.
LCT mk.6 is not very different from other marks of Landing Craft, Tank. Like the rest, it has 2 20mm Oerlikon guns for self-defence and can beach itself to unload the tanks.