Unfortunately it has no Zeiss optics so that's what we get for the price.
That's why I'm getting the XL version of the 640 which does have a Zeiss lens, worth the extra ?50 for 13MP photos.
i dont know if that is how it suppose to be, but when i zoom in.. the picture is realy in a bad resolution
It's because you are trying to take a wide landscape photo which unfortunately the sensor and 8MP camera is not the best suited for. I have the same problem with my old Lumia 630 and find detail is fine with close shots of objects and people but poor with landscapes/scenery. There are a few things you can do to improve them:
1) Try lower the camera to focus on closer objects, in your photo you have too much sky light.
2) Download Photoshop Express (free)
app which has powerful sharpening/noise reductions tools. Some of these features used to be paid only but I registered within the Adobe Login and got all the features now free.
3) Download Fotor (free)
app and use the Enhance, FX Effects, Adjust and Tilt-Shift options to make your landscape scenery photos look more stylish/filtered if you are planning on posting them on Social Media.
Even mobile flagships can struggle taking in so much data with a small Lens but the Lumia 640 Camera is not designed to be a pro camera. You could always upgrade to the 640XL which has a better Zeiss 13MP camera.