how to separate object in blender

1. press tab to enter the edit mode
2. select the object you want to separate
3. click right mouse button or press the p directly to separate the object

there are three kinds of separation:

1. Selection (if you want to separate the object by selection, choose this)
2. By Material
3. By Loose Parts

reference

https://docs.blender.org/manual/en/latest/modeling/meshes/editing/mesh/separate.html