import arcpy
mxd = arcpy.mapping.MapDocument(r"C:UsersP51DesktoptestingLABEL.mxd")
df = arcpy.mapping.ListDataFrames(mxd,"Layers")[0]
layer = arcpy.mapping.ListLayers(mxd, "point10", "Layers")[0]
layer.showLabels = True

Runtime error  Traceback (most recent call last):
File "<string>", line 4, in <module>
File "c:program files (x86)arcgisdesktop10.4arcpyarcpyutils.py", line 182, in fn_
    return fn(*args, **kw)
File "c:program files (x86)arcgisdesktop10.4arcpyarcpymapping.py", line 1517, in ListLayers
    result = mixins.MapDocumentMixin(map_document_or_layer).listLayers(wildcard, data_frame)   File "c:program files (x86)arcgisdesktop10.4arcpyarcpyarcobjectsmixins.py", line 843, in listLayers
    raise TypeError(str(type(dataframe))) TypeError: <type 'str'>

ListLayers (map_document_or_layer, {wildcard}, {data_frame})

layer = arcpy.mapping.ListLayers(mxd, "point10", "Layers")[0]

df = arcpy.mapping.ListDataFrames(mxd,"Layers")[0]

layer = arcpy.mapping.ListLayers(mxd, "point10", df)[0]