My wifi only runs in kbit, why?

You should decide on the reference unit.

Kilobit/s and Kilobyte/s make a difference with factor 8.

The transfer rate between terminal and WLAN access point depends on many factors.
– Protocol used
– distance and spatial conditions between terminal and access point
– other Wi-Fi networks present in the environment that cause interference because they operate on the same channel
…

In most cases, this is triggered by the local conditions and the signal strength thereby impaired. Each object in the visual connection between the terminal and the access point is an obstacle from which the radio waves are reflected and thus weakened. So every wall is an obstacle. The radio waves must then reach the target via reflections. (penetration of masonry etc. is just a bonus. which then also depends on the construction material. The more steel present in the masonry, the lower the penetration.)