If you go to the Beko website manuals section by clicking here, and find the manual for your appliance, you should be able to get the information you need.
If the slotted part at the back is the bulb cover, I think you may find that it simply slides or clips out to reveal the bulb. I'm not familiar with a Beko fridge, but that seems to be how other makes are done. The screw I imagine is there to hold the whole thing in place. The instructions will say.
I found out you just need to slide something thin down each side to release the cover and then it comes off quite easily. It's not too clear from the instructions, but there's actually a handy video I found where someone shows clearly how it's done:
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