I have basic question regarding PCIe devices connections, This is being said, PCIe has 256 Buses, each bus can have 32 devices and each device can have 8 functions.
Since this is said, PCie is point to point connection, my question is how I can connect 5 physical devices over one PCIe bus
PCIe switches can be used in the case you describe.
This PCI Express Basics & Background presentation has more details and shows example topologies.
In case of Switch, each EP will be connected to new physical bus. Even with switch I don't see more than one PCIe EP connected to single bus
The general case is the one you mentioned with a single Endpoint alone on its bus, as the whole point of PCIe was to move to point-to-point physical links.
I can think of two specific cases with multiple Endpoints on a bus (there might be more):
If you consider not only Endpoints but Devices: the PCI-to-PCI virtual bridges inside a switch or in the Root Ports are also all connected to a single internal bus.