Hard wax oil is something in between varnish and oil. It provides a warm wood colouration similar to oil, and leaves a protective film on top of the wood, strengthening the resistance to water, chemicals and general wear.
Avoid direct sunlight on the floor, pull down curtains if needed. Avoid a cross draft to reduce the spread of dust, and the material doesn’t dry too quickly. Vacuum the floor carefully.
You will need a short-haired mohair roller of good quality, an extension bar, a brush and a roller tray. Have some paper and a plastic bag handy in case of spills and somewhere to place the tools when you have finished.