Creating this model can be done with very few features. An extrude, revolve and revolve cut with a cosmetic thread would be the minimum. In the video you will see the hole wizard being used; the hole wizard is a tool that students don't like, but it is very powerful; especially where a series of holes are required, may be a little OTT here.
The base extruede can be constructed from a hexagon. A sketch tool is available for this, set the number of sides and an inscribed circle. The circle dimensioned will set the distance across flats; the hexagon is contrlled in size but will spin (if the centre is at the origin). Pick any line and add a horizontal relation. The sketch should be fully defined. A centre circle could be drawn to create the through hole.
The flange can be created by revolving about the centre line. Sketch a construction line and the shape of the flange. Revolve this; it does not matter that the geometry overlaps. The sketch could also include the edge fillet.
The chamfered corners can be produced by a revolved cut feature, in this case make sure a plane is selected that runs through the flat face of the hexagon and not a corner. Sketch the triangle with the corner point coincedent to the top edge of the hexagon. draw a centre (construction line) and select the revoloved cut feature.
The hole wizard and fillet are added. The hole wizard is discussed else where (see T Nut blog) and in the video. The hole wizard tool requires the input of more information than many of the Solidworks tools and can be off putting to start with; when you have become more familiar with it you will realise how useful it is.